A man was dumped at a Staten Island hospital with what turned out to be a fatal gunshot wound, police said Thursday.

The 36-year-old victim, whose name was not released, was unconscious when he was dropped off at Staten Island University South Hospital by his girlfriend and an unknown man at around 8 p.m. Wednesday, according to police.

Hospital staffers first thought he had been stabbed in the arm — but then found a bullet lodged in his chest, cops said.

Investigators were working to figure out how the man, who was pronounced dead at the hospital, was shot.

No arrests have been made.