This Wednesday, Nov. 1, 2017, image released by the Thornton Police Department shows shooting suspect Scott Ostrem at a Walmart in Thornton, Colo. Colorado authorities identified Ostrema as the man who police say nonchalantly walked into the Walmart and immediately opened fire with a handgun, killing several. (Thornton Police Department via AP) 
People stand across the street from a shooting investigation at a Walmart store, Wednesday, Nov. 1, 2017, in Thornton, Colo. Several people were killed in a shooting inside a suburban Denver Walmart on Wednesday night, forcing customers to either hide in the store or frantically run for the doors. Thornton police advised people to stay away from the area as dozens of police cruisers and emergency vehicles raced to the scene. (Andy Cross/The Denver Post via AP) 
Walmart employees gather together outside away from the scene of the Walmart store where a shooting occurred inside the store, Wednesday, Nov. 1, 2017, in Thornton, Colo. Thornton police tweeted Wednesday night that they were responding to a shooting with “multiple parties down.” They advised people to stay away from the area as dozens of police cruisers and emergency vehicles raced to the scene. (Helen H. Richardson/The Denver Post via AP) 
Police guard the front entrance to Walmart where a shooting occurred inside the store, Wednesday, Nov. 1, 2017, in Thornton, Colo. Thornton police tweeted Wednesday night that they were responding to a shooting with “multiple parties down.” They advised people to stay away from the area as dozens of police cruisers and emergency vehicles raced to the scene. (Helen H. Richardson/The Denver Post via AP) 
A father and his scared daughter, who were customers inside Walmart, are escorted out of the parking lot and away from the scene of the Walmart store where a shooting occurred inside the store, Wednesday, Nov. 1, 2017, in Thornton, Colo. Thornton police tweeted Wednesday night that they were responding to a shooting with “multiple parties down.” They advised people to stay away from the area as dozens of police cruisers and emergency vehicles raced to the scene. (Helen H. Richardson/The Denver Post via AP) 
Walmart employees and customers that were inside the store wait to hear what to do from police as they stand behind police tape outside of a Walmart store where several people were killed in a shooting, Wednesday, Nov. 1, 2017, in Thornton, Colo. Investigators, who have not released any details about the circumstances of the shooting, were reviewing security footage and interviewing witnesses to get a description of the shooter. (Helen H. Richardson/The Denver Post via AP) 
Darlene Jackson sits on an overturned shopping cart as she and fellow shoppers and employees gather outside after a gunman opened fire in Walmart in Thornton, Colo., Tuesday, Nov. 1, 2017. Police in Thornton announced the shooting in a tweet Wednesday evening and advised people to stay away from the area. Dozens of police cars and emergency vehicles converged at the store. (AAron Ontiveroz/The Denver Post via AP) 
Walmart customers and employees are held back while emergency crews and police work on the grounds of Walmart during a shooting in Thornton, Colo., Wednesday, Nov. 1, 2017. Police in suburban Denver say they are responding to a shooting at a Walmart with “multiple parties down.” Dozens of police cars and emergency vehicles converged at the store. (John Leyba/The Denver Post via AP) 
Emergency crews and police work at the scene in response to a shooting at Walmart in Thornton, Colo., Wednesday, Nov. 1, 2017. Police in suburban Denver say they are responding to a shooting at a Walmart with “multiple parties down.” Dozens of police cars and emergency vehicles converged at the store. (John Leyba/The Denver Post via AP) 
Walmart employees and customers that were inside the store wait to hear what to do from police as they stand behind police tape outside of a Walmart store where several people were killed in a shooting, Wednesday, Nov. 1, 2017, in Thornton, Colo. Investigators, who have not released any details about the circumstances of the shooting, were reviewing security footage and interviewing witnesses to get a description of the shooter. (Helen H. Richardson/The Denver Post via AP) 
Several people were killed in a shooting inside a Walmart, forcing customers to either hide in the store or frantically run for the doors, Wednesday, Nov. 1, 2017, in Thornton, Colo. Thornton police advised people to stay away from the area as dozens of police cruisers and emergency vehicles raced to the scene. (AP Photo/P. Solomon Banda) 
Marlena Fobb, front right, of Thornton, Colo., who was shopping at the time of the shooting at a Walmart store, hugs an unidentified store employee Thursday, Nov. 2, 2017, in Thornton, Colo. The store was the scene of a shooting Wednesday night when a man walked in and opened fire with a handgun. The suspect was arrested Thursday, about 14 hours after fleeing the store. Fobb’s husband, Jason, left, holds the vacuum cleaner that the couple was purchasing at a self-check stand when the suspected gunman entered the store. (AP Photo/David Zalubowski) 
Employees head in to a Walmart store Thursday, Nov. 2, 2017, in Thornton, Colo. A man suspected of fatally shooting several inside the suburban Denver Walmart on Wednesday, was arrested 14 hours later following a brief car chase Thursday that ended at a congested intersection, police said. (AP Photo/David Zalubowski) 
Marlena Fobb, a customer from Thornton, Colo., who was trying to buy a vacuum cleaner at a Walmart store, talks about seeing a gunman entering the store as Fobb returns to pick up her vacuum Thursday, Nov. 2, 2017, in Thornton, Colo. The store was the scene of a fatal shooting Wednesday night. The suspect was arrested Thursday, about 14 hours after fleeing the store. (AP Photo/David Zalubowski) 
Nick Noblett, left, and Tonya Brown talk Thursday, Nov. 2, 2017, about being in the Walmart store behind them during a fatal shooting Wednesday evening in Thornton, Colo. The couple returned to the store to pick up their belongings after escaping when the gunman entered. (AP Photo/David Zalubowski) 
Jason Fobb, second from left, comforts his daughter, Angelique, as Fobb’s wife, Marlena, right, embraces her daughter Destiney outside a Walmart store Thursday, Nov. 2, 2017, in Thornton, Colo. The couple was in the store at the self-check stand Wednesday night when a man walked in and opened fire with a handgun, killing several. The suspect was arrested Thursday, about 14 hours after fleeing the store. (AP Photo/David Zalubowski) 
This Thursday, Nov. 2, 2017 photo released by the Thornton Police Department shows Scott Ostrem, suspected of fatally shooting several people inside a Thornton, Colo., Walmart Wednesday night. He was arrested 14 hours following a brief car chase that ended at a congested intersection, police said. (Thornton Police Department via AP) 
This undated photo, provided by Aurora Higher Education Center, shows Carlos Moreno. Moreno, a grandfather who years as a maintenance worker at a complex of universities in downtown Denver, was killed during a shooting at a suburban Walmart store Wednesday, Nov. 1, 2017. (Auraria Higher Education Center via AP)
THORNTON | A man suspected of fatally shooting two men and a woman inside a suburban Denver Walmart was arrested 14 hours later following a brief car chase Thursday that ended at a congested intersection during the morning rush hour, police said.
Scott Ostrem, 47, was arrested after police pulled over his car about 5 miles (8 kilometers) from the Walmart store in the city of Thornton, police spokesman Victor Avila said.
The roofing company boss Ostrem said the suspect walked away from his job without warning the morning of the shooting.
David Heidt of B&M Roofing said Ostrem worked in the company’s metal fabrication shop for the last three years without any problems.
He says Ostrem left his work station around midmorning Wednesday without any explanation and never came back. The shooting happened at the Walmart that evening.
Heidt says Ostrem was a good and quiet worker who was skilled at his craft of marking metal flashing for roofs.
Authorities have identified the three people who were fatally shot at the Walmart.
Coroner Monica Broncucia-Jordan said Thursday that 52-year-old Pamela Marques, 66-year-old Carlos Moreno, and 26-year-old Victor Vasquez died in Wednesday night’s shooting.
Moreno was a grandfather who was a longtime maintenance worker at the Auraria Higher Education Center. It houses various state colleges and universities in downtown Denver.
Spokesman Blaine Nickerson says he was well-known and respected on campus.
Television footage showed Ostrem, with close-cropped hair and wearing a red polo shirt, standing silently and staring down as he was handcuffed. Avila declined comment on whether Ostrem had a weapon when he was arrested.
Police had yet to determine a motive for the shooting, which occurred late Wednesday inside the busy Walmart in a busy Thornton shopping center. The federal Bureau of Alcohol, Tobacco, Firearms and Explosives joined local police in the investigation.
Witnesses said a man walked into the store, opened fire and fled. Dozens of shoppers and employees dropped to the ground and rushed to escape as police cruisers and ambulances raced to the scene.
Aaron Stephens, 44, was in the self-checkout line when he heard a single shot followed by two bursts of gunfire. Then people ran for the store’s exits.
“The employees started screaming. Customers were screaming. They were running like crazy, and I ran out too because I didn’t want to get killed,” he said.
Two men died inside the store, and a woman died later at a hospital, police said. Their identities were not immediately released, and it was not known if the suspect knew them.
No Walmart workers were injured in the attack, said spokesman Ragan Dickens. Dickens added that there is no evidence that Ostrem ever worked for Walmart. The store remained closed Thursday, he said.
Authorities identified Ostrem as a suspect after reviewing surveillance footage from the store.
Avila said police went to a Thornton apartment early Thursday and did not find Ostrem there, but received an anonymous tip that he was driving a red Mitsubishi in the area and quickly spotted him. The brief chase ensued.
Ostrem was taken away in a police car and the car he was driving was towed away on a flatbed truck.
Avila said Ostrem had a minor criminal history but did not elaborate. Court records show a charge of resisting arrest against Ostrem in 1999 was dismissed. Records also show Ostrem filed for bankruptcy in 2015.
Ostrem worked for a Denver-based roofing company as a field employee until 2014, said Sandra Runyon, an administrative assistant at Tecta America Colorado Commercial Roofing. Runyon said the company had had no contact with Ostrem since he left. She didn’t provide additional details.
Residents of the apartment building where Ostrem lived in a third-floor unit described him as unfriendly and occasionally hostile.
Teresa Muniz, a 54-year-old meat processor, said most tenants in the building are friendly with each other but Ostrem never returned her greetings. Several times, he swore at people for sitting in the outdoor stairways or leaving laundry in communal machines, she said.
“He wasn’t a friendly person,” Muniz said. “It has to be a really lonely life, and he didn’t seem to have anybody. Being angry all the time. That’s what he seemed like, always angry.”
Muniz said she sometimes saw Ostrem carrying a bow and set of arrows or a shotgun into or out of his apartment.
Gerald Burnett, a 63-year-old retiree who lives in a first-floor unit, said he was sitting on the stairs drinking coffee one morning when Ostrem came down the steps. Ostrem told him to move and cursed at him, Burnett said.
“Dude had an attitude, big time,” Burnett said. “He’s the type of person if you said ‘good morning,’ he wouldn’t say nothing. If you greeted him, he wouldn’t say anything back. I just learned not to even talk to the clown.”
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Associated Press writers Tatiana Flowers and Colleen Slevin contributed to this report.