It happened right before 6 p.m. Sunday.
WATCH surveillance video recorded moments before the attack
The grainy video shows the victim being followed. Then, out of the frame, police say, he was bludgeoned.
Not wanting to show her face, nor give her name, Donna told ABC11's sister-station WPVI the attack happened right outside of her home.
"They hit his head into the wall so hard that I felt it in my house, on the second floor," she said.
When Donna ran out to help the man who they call Kevin, his pockets were turned inside out and the teens scattered.
Homeless man beaten to death by group of teens in Mayfair Sunday evening. Two arrests, police looking for more.— Katherine Scott (@KScott6abc) November 28, 2017
"They ran away laughing like it was funny," said Donna "(They were) saying, 'We got him.'"
Beloved by those who lived on the block, Kevin was taken to Jefferson Torresdale Hospital. On Monday, the hospital confirmed he had died.
"I can't believe it, that guy has been up and down this neighborhood," said resident Matt Giampa. "Like why now, why right here?"
Police arrested two of the teens after the attack and are looking for the others involved in the brutal murder.
The violence has left residents rattled.
"My daughter's bus stop is right over here," said Giampa. "So that's another concern for me."