Thornton police have arrested a 47-year-old suspect in the apparently random Walmart shooting in which a man almost casually shot two men and a woman, killing them, before turning around and walking out of the store Wednesday night.

Scott Ostrem, 47, was arrested at around 8 a.m. Thursday near 72nd Avenue and Federal Boulevard.

Joe Amon, The Denver Post The Fobb family Angelique 13, Jason Fobb, Destiney 9, Marlena Fobb. Marlena Fobb is hugged by her daughter Destiney 9, as she tells her story of being in the check-out line with her husband Jason next to a man that was shot and killed in the shooting at Walmart in Thornton. "He saved my life, she said, talking of her husband, If he hadn't of threw me to the ground we were gone."

Provided by Thornton Police Department Scott Ostrem

Provided by Wheat Ridge Police Department Scott Ostrem in 2013



Provided by Wheat Ridge Police Department Scott Ostrem in 2014

John Leyba, The Denver Post Rochelle Ginsner holds her daughter Danielle Carey, 16, an employee, after they were released from the parking lot at Walmart after a shooting at the store on Nov. 1, 2017.

Helen H. Richardson, The Denver Post Walmart employees and customers head away from the scene outside of the Walmart store where a shooting occurred inside the store at 9901 Grant Street on Nov. 1, 2017 in Thornton.



AAron Ontiveroz, The Denver Post Darlene Jackson sits on an overturned shopping cart as she and fellow shoppers and employees gather outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post Employees Jose Delgado and Alexandra Adams stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

Joe Amon, The Denver Post Police at shooting in Walmart on Nov. 1, 2017 in Thornton.



RJ Sangosti, The Denver Post Witnesses walk from a bus to Thornton Civic Center after two men were killed during a shooting inside the Walmart Super Center iNovember 1, 2017 in Thornton.

John Leyba, The Denver Post Family and friends wait on a hill to hear word from their loved ones as emergency crews and police patrol the grounds of the Walmart after a shooting at the store on Nov. 1, 2017

Helen H. Richardson, The Denver Post A father and son, 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 at 9901 Grant Street on Nov. 1, 2017 in Thornton.



Helen H. Richardson, The Denver Post Employees gather together outside away from the scene outside of the Walmart store where a shooting occurred inside the store at 9901 Grant Street on November 1, 2017 in Thornton, Colorado. Two people were killed and one taken to the hospital after a shooting that started just around 6:00pm.

Helen H. Richardson, The Denver Post Police officers help a disabled man leave the parking lot outside of the Walmart store where a shooting occurred at 9901 Grant Street on Nov. 1, 2017 in Thornton.

AAron Ontiveroz, The Denver Post A Thornton police officer gives instructions to people as they stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.



Helen H. Richardson, The Denver Post 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 the Walmart store where a shooting occurred Nov. 1, 2017 in Thornton.

Helen H. Richardson, The Denver Post Walmart employees and customers head away from the scene outside of the Walmart store where a shooting occurred on Nov. 1, 2017 in Thornton.

AAron Ontiveroz, The Denver Post A Thornton police officer watches as people are instructed to leave the parking lot after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton.



AAron Ontiveroz, The Denver Post People stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post Employees exit the parking lot after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post People stand outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.



John Leyba, The Denver Post Employees and shoppers are released from a holding area in the Walmart lot. Emergency crews and police on the grounds of the Walmart in Thornton on Nov. 1, 2017 during a shooting.

AAron Ontiveroz, The Denver Post A man in a Rascal is helped out of the parking lot as shoppers and employees gather outside after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton.

Andy Cross, The Denver Post Bystanders on a hill at 98th and Grant across the street from a shooting investigation at a Walmart in Thornton on Nov. 1, 2017.



Andy Cross, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.

AAron Ontiveroz, The Denver Post People are escorted out after a gunman opened fire near the Halloween section of Walmart at 99th and Grant Street in Thornton on Nov. 1, 2017.

Helen H. Richardson, The Denver Post Onlookers watch police activity at the scene of a shooting inside the Walmart at 9901 Grant Street on Nov. 1, 2017 in Thornton.



Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.

Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.

Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart in Thornton on Nov. 1, 2017.



Joe Amon, The Denver Post Police investigate the scene of a fatal shooting at the Walmart Super Center in Thornton on Nov. 1, 2017.

Helen H. Richardson, The Denver Post A young girl walks through the parking lot away from the scene outside of the Walmart store where a shooting occurred on Nov. 1, 2017 in Thornton.

Helen H. Richardson, The Denver Post 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 on Nov. 1, 2017 in Thornton.



Helen H. Richardson, The Denver Post THORNTON, CO - OCTOBER 1 - 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 on November 1, 2017 in Thornton, Colorado. Two people were killed and one taken to the hospital after a shooting that started just around 6:00pm.

John Leyba, The Denver Post Adams County Sheriff on the grounds of the Walmart in Thornton on Nov. 1, 2017 talking to witnesses after a shooting inside the store.

John Leyba, The Denver Post People are taken away from the Walmart on a bus on Nov. 1, 2017 in Thornton after a shooting inside the store.



Helen H. Richardson, The Denver Post Police guard the front entrance to Walmart where a shooting occurred inside the store at 9901 Grant Street on Nov. 1, 2017 in Thornton.

Ostrem was seen Wednesday night driving a red 2017 Mitsubishi Mirage with Colorado license plate number 882TQB, and police asked the public to keep an eye out for the car and Ostrem, warning that he was “armed and dangerous.” Ostrem was stopped on the street Thursday morning while driving that vehicle.

Police searched Ostrem’s last known address, in the 7100 block of Samuel Drive in Denver, on Thursday morning, Thornton police spokesman Victor Avila said at a 9 a.m. news conference. Ostrem was not at home.

Officers from several local departments were in the area Thursday morning when a citizen called Thornton police to report that Ostrem might be nearby, at 72nd Avenue and Federal Boulevard. The red Mitsubishi was among dozens of cars stopped in morning commute traffic near the intersection.

Ostrem was stopped and arrested without incident, Avila said. A loud noise reported by bystanders was a SWAT unit’s flash-bang grenade, used as a distraction during the arrest, Avila said.

A tow truck promptly removed the Mitsubishi from traffic. Avila would not say what was seen inside the car.

Ostrem allegedly used a handgun to shoot the three people in Walmart, Avila said.

According to several witnesses the 6:10 p.m. shooting at the Walmart Supercenter, 9901 Grant St., appeared to be random, Avila said.

“He walked in very nonchalantly with his hands in the pockets, raised a weapon and began shooting. Then he turns around and walks out of the store,” Avila said. “From what we have right now it appears to be random. It’s a crazy world we live in.”

Walmart shooting incident, person and vehicle of interest, remain anonymous, call Crime Stoppers 720-913-7867 pic.twitter.com/PFNbEALpbG — Thornton Police Dept (@ThorntonPolice) November 2, 2017

Aaron Stephens, 44, was in the self-checkout line at Walmart when he heard a single shot fired, followed by more bursts of gunfire. He said customers started screaming and running for the exits.

“I was scared,” Stephens said. “I feared for my life.”

Hundreds of emergency responders ringed the Thornton Town Center shopping center for hours after the shooting was reported: “multiple parties” were down.

The victims have not yet been named. The woman was taken to a local hospital for treatment but she later was pronounced dead, Avila said Thursday morning.

They were the only people who were shot, he said. Other people were treated for anxiety-related issues.

“We are relieved that an arrest has been made in this case,” Walmart said in a statement Thursday. “The local authorities have done an outstanding job. This has been a tragic situation. Our thoughts and prayers continue to be with the families who lost loved ones and on supporting our associates. We will continue assisting law enforcement however we can.”

No Walmart employees were injured in the shooting, company spokesman Ragan Dickens said. He said employees receive training for shooting situations but declined to provide details of that training. The company is making counselors available for impacted employees.

It is unknown when the store will reopen, as the investigation is ongoing, he said.

Maurice Sartor, 45, said he was walking toward the exit Wednesday evening when he heard the first rounds drop.

“As soon as I heard them, I started to run,” he said Thursday morning as stood outside the store.

Sartor, who is homeless, said he had just purchased a sleeping bag Wednesday evening, and he ran out the doors when he heard gunfire.

“Everyone started to run,” he said. He said he yelled to people approaching the store, “Get in your car and get out of here!”

Sartor said he came across kids outside the store and asked drivers to ferry them away from the scene.

“I was trying to protect myself at first, and then I came across some kids,” he said.

Sartor said he was shot in the abdomen years ago during a robbery at the used tire shop where he worked in Oklahoma City, so he immediately recognized the sound of gunfire.

Police questioned Sartor, he said, and then they took him to a local hospital for a checkup after he said he suffered PTSD and anxiety. He said he was released from the hospital Thursday morning and had returned to the Walmart to get his sleeping bag. No one was allowed inside the store.

The store was closed for the day, but dozens of cars remained in the parking lot.

One by one, people who had fled the scene Wednesday night returned to retrieve them.

A woman who identified herself only as Holly returned to her car about 7:45 a.m. She said she works for a vendor with a business inside Walmart and was working Wednesday evening.

“I saw a gentleman go down,” she said, and heard a shot. She said she knew it was gunfire after watching and hearing the video reports from the Oct. 1 mass shooting in Las Vegas over and over.

Everyone started running, she said. She and others near her ran out a back door. “It was a nightmare,” she was. “It was terrifying.”

Avila implored anyone with information about Ostrem to call police as soon as possible.

According to court records, Ostrem declared bankruptcy in 2015, but he does not have a lengthy criminal record.

In 2013, he was arrested for driving while ability impaired, according to court records.

Anyone with information regarding this investigation is asked to call the Thornton police tip line

at 720-977-5069.

Denver Post reporters Tom McGhee and Danika Worthington contributed to this story.