The 10-year-old boy told his mother the homeless man at the gas station had hit him.
They were both at the Sunoco station at 5338 N. Fifth St. in Olney on Tuesday, offering to pump patrons' gas for spare change. They argued over who would pump gas next.
Investigators, reviewing hours of footage from the station, said there was no evidence the 51-year-old man ever hit the boy.
But the boy's mother needed only his word.
That evening, she and friends and family members - up to seven of them - pulled up at the station in a friend's minivan and spilled out with Mace, a hammer, and a rocking chair leg in hand, police say.
Video from the station captured the brutal, agonizingly prolonged beating that followed and that left the 51-year-old victim near death in a medically induced coma.
And as the man lay unconscious and bleeding on the ground, one of the women in the van pulled the boy back toward the man to show him: This is what we did for you.
"Just watching, you see the viciousness of it," said Lt. Dan Brooks of Northwest Detectives.
Footage from the station's surveillance camera shows the group running from the minivan toward the victim, with the boy's mother, 34-year-old Aleathea Gillard, swinging the rocking chair leg, police said. A close family friend, Shareena Joachim, 24, carried the Mace, they say.
Joachim was the first to reach the man as he stood by the door of the station's convenience store. She tried to spray the Mace in his eyes - but missed, hitting someone in her group instead, police said.
As she backed off, Gillard and others moved in.
Gillard swung the chair leg into the victim's head and face, hitting him over and over, until the chair leg broke over his head, police said. One woman beat the victim with what police believe is a hammer. Two juveniles, police said, stomped and kicked him in the head.
As the group pulled back, Joachim pulled the boy by his red-and-yellow jacket toward the victim, let him look, and then ushered him back into the van before it pulled away.
Police found the minivan outside Einstein Medical Center - where the victim had been taken - shortly after the attack, with Gillard, 34, and Joachim, 26, inside. They were arrested and charged with attempted murder and related crimes. Both gave statements to police, Brooks said.
Police are still searching for three other people seen in the video: the woman with the hammer, and the juveniles who kicked and stomped on the victim.
The victim remained in a medically induced coma Friday with multiple skull fractures and other broken bones, police said.
Police on Friday released the video; it can be seen at philly.com/assaultvideo.
Anyone with any information is asked to call Northwest Detectives at 215-686-3353.