Surveillance video shows a man approaching a woman on the deserted subway platform. The woman said he asked to borrow a lighter.
After returning the lighter, the man suddenly chokes her and punches her repeatedly. He grabs the woman's ankles and drags her across the platform and throws her onto the tracks. Then he reaches into her purse.
The woman climbed to safety with only minor injuries.
"He picked up her cellphone and strolled out of the station. He didn't even run," said Southeastern Pennsylvania Transportation Authority Police Chief Thomas Nestel.
After a citywide manhunt, Philadelphia Police arrested 37-year-old William Clark Thursday. Police plan to charge him with aggravated assault, theft and related counts.
The motive for the attack was unclear.
Two people died in separate incidents in New York in December when they were pushed onto train tracks and fatally struck by trains.