Surveillance video captured it all outside the 69th Street Terminal in Upper Darby Thursday evening around 5:20 p.m.
Police say 58-year-old Cordelia Chisholm, of Yeadon, bumped into a 22-year-old woman who was talking on a cell phone.
Chisholm becomes annoyed, says something, and then moves to a seat further back, but she continues to yell at the young woman on the phone.
Less than a minute later she gets up, pulls a fully loaded .38 revolver from her bag, and confronts the woman on the phone. She gets up and the two get into an argument.
All the while, police say, Chisolm is waving the gun around with at least four young children and other passengers only a few feet away.
"She's waving that gun and, at any moment, a bullet [could] go off, hitting any one of those children or anybody else," said Upper Darby Police Superintendent Michael Chitwood.
As the two women struggled, police say 32-year-old Rasheen Bingham of Lansdale stepped in. He had just picked up his two young sons from the barber shop and told Action News his main concern was their safety.
"She said 'This old lady will put a bullet in your mouth," Bingham told Action News. "She did say that, but I thought it was still talk until she actually pulled the gun out."
Bingham not only broke up the fight, but managed to get Chisolm off the bus. The police arrived on the scene and arrested her as she was walking away.
Investigators are calling Bingham a hero, a man who did what many people won't - help others in trouble.
"I wouldn't call myself a hero. I reacted the way I thought I was supposed to react," he said.
Chisholm did not have the proper permit to carry the gun. She's being held on $50,000 bail and facing serious jail time.