A man was shot to death in Queens Saturday night.

The unidentified victim — a man in his 20s — was shot twice in the head behind a three-story apartment building on Grassmere Terrace in Far Rockaway around 8:15 p.m., according to NYPD sources.

He was pronounced dead at St. Johns Hospital less than an hour later, the sources said.

The victim had been walking with the suspect, who pulled out a gun and opened fire, sources said.

The killer fled on foot and cops were reviewing security footage of the murder as they hunted for the suspect.