A 24-year-old man was in critical condition Tuesday after he was stabbed on a Staten Island bus, police said.

The victim, who was not immediately identified, was at the back of the bus when he got into a fight with another man about a seat.

The suspect stabbed the victim five times in his chest, as well as his hands or arms, according to authorities.

The suspect then ran off the S74 bus, which was idling at the intersection of Canal and Water streets, a bus stop, an MTA spokesman said.

The victim was taken to Richmond University Medical Center where he was in critical condition.