It happened just after 4 p.m. Wednesday near Southern Boulevard and Westchester Avenue.
The bus driver is 14 year veteran, and was slashed in the right arm. He was driving a BX 5 bus and there were passengers on it.
Bus driver told the union that the suspect was on the bus. He reached down to make an announcement and the suspect slashed him.
He said it was not a robbery attempt. He doesn't know why the guy slashed him.
A Union representative says there was a partition on the bus, which prevented the suspect from getting too close to the driver.
The driver was taken to Lincoln Hospital and his injuries are not life threatening.
The suspect dropped his cell phone and left it behind.
The bus driver thinks he was slashed with a razor blade.