9NEWS obtained exclusive video of the man's arrest. The video was taken by Kyle Wersen, a shopper who saw the incident unfold around 1:46 p.m. at the Broomfield Walmart on West 121st Avenue
"[It was] perfect timing," Wersen said. "We happened to be there and see the whole thing."
Walmart shoppers scrambled for safety as smoke filled the aisles.
"A lot of people start screaming and then I hear fire thrown around and then it starts going," Wersen said. "It gets pretty big too. It smelled like burning wood. The fire was big and tall. That's all I noticed. It reached up over the clothes and stuff so you could see it pretty visibly."
Wersen and the other shoppers were evacuated.
Wersen continued to record video as Broomfield police arrested the 28-year-old man who they say started the fire.
The suspect's name has not been released.
"We were just recording," Wersen said. "I saw him getting arrested and I was like, 'oh we better get over there and check that out.' He was a big guy."
At one point in the video, a woman in purple is seen approaching the officers and the suspect.
"It looked like maybe she knew him or something," Wersen said.
Officers ordered the woman to get back as they restrained the handcuffed suspect.
Police say the same man threatened two shoppers with a knife.
Witnesses and a Walmart spokesperson say one of those shoppers was a young boy.
"The guy took the kid almost hostage," Wersen said. "He had like a knife to his throat. He was small and he was being carried. His mom looked very upset and frazzled. Her face was red and everything."
Walmart spokesperson Ashley Hardie released the following statement:
Our top concern is always the safely and security of our customers and associates. We are grateful the child appears to be doing OK.
We appreciate the quick response of Broomfield police and fire departments. We are actively working with them as they conduct their investigation.
The fire was out quickly and only caused minor damage.
"There were flames by the woman's department," Dominique Le'nior said. "Who would set a fire on Labor Day at Walmart?"
Wersen also wonders why anybody would do this.
"I didn't believe this was really happening," Wersen said.
The Walmart remained closed for several hours Monday and customers were turned away as Broomfield police and firefighters continued their investigation.
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