Robert Cox and his 2-year-old son had just finished shopping at the Germantown Best Buy when another shopper, a man high on PCP, grabbed the toddler and ran.

Doing what any dad would, Cox ran after him. He caught up seconds later, grabbing the man as he headed through the store’s two sets of doors. The man threw the boy into one door so hard that the pane cracked in a spider-web pattern. They wrestled, but the man threw punches and fled.

The man didn’t make it far, police said. Just outside, a group of people took him down.

The suspect, Jermaine L. Palmer, 23, later told police that because of the effects of the PCP, he thought the child was his own, according to the arrest records. The boy had cuts on his chin and needed bandages.

The terrifying scene, which unfolded Wednesday afternoon, was described in papers filed Thursday in Montgomery County District Court.

Palmer, who was charged with child abduction, assault and other counts, was being held Thursday night, according to court records and jail officials.

Just after 3 p.m. Wednesday, Palmer had walked into the Best Buy store on Frederick Road in with his infant child, 9-year-old stepchild and girlfriend, according to an arrest affidavit written and signed by Montgomery Police Officer John Staiger. They began shopping.

Cox, 37, and his son were already there. He purchased items and began to return his shopping cart, stopping briefly to allow his son to play with the cart.

About the same time, Palmer, who was nearby, bolted toward the door and fell face first, court papers say.

In the commotion, the 2-year-old “walked a few feet away from his father to look at what was happening,” Staiger wrote in his arrest affidavit. Palmer “stood up and grabbed [the child] and began running out the store with the child in his arms.”

The child’s father gave chase, catching Palmer between the doors at the front of the store. That’s when Palmer threw the child into the outer door, police said.

The boy’s father and Palmer wrestled, with Palmer punching him as he escaped from the store, police said. By that time, 30 to 50 customers and workers had heard the commotion and run to the exits to help the victims or watch what was going on, police said.

Palmer was held by people until police arrived, according to authorities. He has an arrest record dating to at least 2006 that includes convictions for assault and disorderly conduct, according to online court records.

He apparently was not badly injured by the people who took him down. He did not require hospitalization, said Officer Howard Hersh, a police spokesman.

Palmer’s girlfriend and Cox gave similar descriptions of Palmer’s actions to police, Staiger said. The girlfriend added that before Palmer bolted from the store, he seemed confused, leading to an argument between the two.

Police also said that video surveillance from the store confirmed what the girlfriend and boy’s father told them.

The Washington Post generally does not name victims or witnesses of crimes, but Cox’s name was widely disseminated by police. He could not be reached Thursday.

Staff researcher Jennifer Jenkins contributed to this report.