A group of thugs snuck up behind an off-duty cop on a Queens street last night, hitting him in the head, authorities said.

The attack occurred at 9:05 p.m. on 175th Street near 109th Avenue in Jamaica, where three to four men attacked the cop with what might have been a pipe, authorities said.

The officer, who suffered a small cut on his head, called 911 and was taken to North Shore University Hospital.

It is unknown whether he had his service weapon with him at the time of the attack, or whether his attackers knew he was a cop.

There were no immediate arrests.