A Washington man has been arrested on a murder charge after he fatally shot a 17-year-old boy who had been returning a BB gun to a Big 5 Sporting Goods store in a Seattle suburb.

Aaron Brown Myers, 51, told police he thought the teen and his friends were about to rob a store and that he was also worried about the safety of his own 13-year-old son, who was in a jujitsu class next to the sporting goods store.

Brown told police that the teens were ignoring his commands and he thought that one of them was "going to kill him," according to a Renton Police Department probable cause statement obtained by USA TODAY on Friday.

But surveillance footage refutes much of Brown's story, police say.

Here's what we know:

Surveillance footage shows teen had put down BB gun: police

Three teenagers were seen making their way toward the main entrance of the Big 5 store, police say the surveillance footage shows.

Myers, who says he's a licensed security guard, was sitting in his car Wednesday to conduct "overwatch" while his son trains because "he has seen numerous crimes occur" in the parking lot, according to the probable cause statement.

The surveillance footage shows Myers approach the teens with a gun in his hand, point it directly at them and then move quickly toward them, police said. One of the boys pulls a BB gun out of his pocket, lays it on the ground and extends his arms out as if to show he has nothing in his hands, police said in the document.

Myers pushes the boy the ground, straddles him and holds him in place as he points the gun at the 17-year-old, who is standing and brings both arms forward, showing that he has nothing in hands, the footage shows. The 17-year-old backs away, with his left hand in the air while his right arm "briefly lowers to his waist area," police said in the document.

"Immediately after ... it is clear that he has been shot because he abruptly jerks his body away from Myers and falls to the ground," the document says.

Based on the footage, the officer writing the document says there was probable cause to arrest Myers on a charge of second-degree murder without premeditation. Myers was arrested and taken to an interview room.

The 17-year-old shot and killed was identified as Hazrat Ali Rohani by Kent-Meridian High School Principal David Radford, according to the Kent Reporter.

Myers cries in interview room, says he 'had a duty to act'

When police read Myers his rights and began trying to interview him, he "was distraught and crying," police said.

"He advised that he was going to 'be sick' and he was given a trash can, where he started to audibly gag a few times," police said, adding that they helped calm Myers down to explain why he shot the boy.

Myers said that when he first saw the boys, he thought one of them had a "Glock" by his side and that they were about to commit an armed robbery.

"Myers felt like he did not have time to call 911, and that he had a duty to act to stop the individuals from hurting someone innocent, and to protect his son, who was in the location next door," according to the police report.

Myers got out of his car and pointed his gun at the three teens, who were still walking toward the store. He said they ignored his repeated commands to put their hands up.

He said that he saw what he believed to be a gun in one of the teen's waistbands and saw the boy "grab the handle of the gun," police wrote.

Myers said he told the teen not to grab the gun but that the boy only "grabbed the gun further." Myers said he believed that the teen was "going to pull it out" and "was going to kill him." That's when the shooting happened.

Myers' case has not made its way to the King County Superior Court and USA TODAY could not find a lawyer representing him. Phone numbers listed in the police report for Myers and his emergency contact rang unanswered Friday.

Teens explain why they had BB guns

The two surviving teens told police that they were at the store to return or exchange Hazrat Ali Rohani's BB gun because he was having some issues with it, according to the police report. One of them also said that he had his own BB gun with him and brought it along so employees could check out a "magazine issue" he was having.

Both friends said they told Myers repeatedly that they were carrying BB guns and that before they knew it, their friend had been shot.

Radford, Rohani's principal, wrote an email to parents and students that he was "deeply saddened to inform you of another tragic passing of one of our students."

“As some of you may have seen the news on Wednesday evening, June 5, Hazrat Ali Rohani was involved in an altercation in Renton, which tragically ended in loss of life," he said, according to the Kent Reporter. "Our thoughts are with his friends and family during this sensitive time."