Update below

Police arrested a bus driver and passenger early this morning in the Bronx after they say a dispute over the bus's air conditioning and a rerouting spilled out onto the street, leaving both men battered, and the driver bleeding from the mouth from an alleged headbutt.

Raymond Wilkerson was driving the 2 train shuttle bus near the Bronx Zoo at around 2:30 a.m. when passenger Gregory Maloney, of East New York, approached him to complain about the air conditioning and the route the bus was taking, cops said, though they could not say the exact nature of his complaints. As the two argued, Wilkerson stopped the bus, and they both got off, cops said.

That's when Wilkerson claims Maloney spat on him, then headbutted him in the face, busting open his lip. Wilkerson allegedly retaliated, punching Maloney and wrestling him to the ground, causing him to hit the back of his head, according to police. Officers arrested both men, and say they found pepper spray on Maloney in the process. Wilkerson is facing a misdemeanor assault charge, while Maloney has been hit with a felony assault charge, plus possession of a noxious substance.

Maloney refused medical attention, according to police, and an MTA spokeswoman said Wilkerson was taken to Montefiore Medical Center. Wilkerson has been released from police custody and is undergoing testing at a bus depot, the spokeswoman said.

Transport Workers Union Local 100 spokesman Pete Donohue noted that bus operators are regularly attacked on the job, citing 62 assaults in the last year, and 120 incidents where passengers spat on drivers.

"Those statistics highlight the fact that operating a bus in NYC can be a dangerous and extremely stressful job," Donohue said.

Donohue's colleague Jim Gannon said the union did not yet have further information on what happened this morning in the Bronx, or on Wilkerson's employment status following the incident.

Update 6 pm:

According to Transport Workers Union official Frank Austin, Wilkerson had disembarked at the end of his route to inspect the bus, as is required of bus drivers at the end of each trip, when he was headbutted by Maloney. He subsequently acted in self-defense, Austin said.