Two city firefighters teamed up yesterday to chase down a mugger who swiped a cellphone from a pedestrian in front of their Greenwich Village firehouse, authorities said.

The men, from Engine Co. 24 and Ladder 5, were in the firehouse at Houston Street and Sixth Avenue at 6 p.m. when they heard the victim scream.

"There was a guy who ran by with a bloody mouth," Lt. Richard Quinn said.

"He was yelling out, 'Help me! Help me!' "

Firefighters Jason Porzsce, a former military police officer, and Adam Karabuber, a former NYPD cop, began running after the suspect, along with the victim, while Quinn called 911.

They caught up with the thug four blocks away, fire officials said. They were soon joined by several of their firehouse buddies, who arrived in their truck and held the suspect for cops.

The victim got first aid at the firehouse. "He wasn't saying much. He was just thankful," Quinn said.