A Metro Transit bus driver allegedly punched a woman passenger twice in the head after she photographed him with her cellphone, according to charges filed by the St. Paul city attorney's office.

James N. Yang, 46, of St. Paul, is charged with fifth-degree assault, disorderly conduct and fourth-degree criminal damage to property.

According to the charges: Metro Transit police responded to the bus' alarm at 11:30 a.m. on Oct. 2, and found the Route 16 bus stopped near University Avenue and Dale Street. Yang allegedly was standing on his seat with a hammer while the woman stood in the aisle yelling and holding a folding knife. They put down their weapons in obedience to police.

Metro Transit spokesman John Siqveland said the altercation occurred after the woman was "verbally critical" of Yang during the trip.

She commented on his attitude when she exited, he said, and the situation escalated. Bus surveillance video showed that the woman re-entered, photographed Yang and exited again.

Yang followed her out, took her cellphone and re-boarded the bus, charges said. The woman and Yang struggled over the phone, and Yang allegedly threw it down. They struggled briefly and Yang allegedly punched the woman twice in the head.

Yang did not work again until Oct. 25 while the incident was being investigated, Siqveland said. He is now working under a "last chance" agreement, will undergo mandatory counseling and could face termination for future misconduct, he said.

Yang has been a bus driver with Metro Transit since 1999, and is a "13-year safe driver" whose only previous discipline was a verbal warning for attendance, Siqveland said.

He must appear in court in January or a warrant for his arrest will be issued.

Chao Xiong