An off-duty police officer on his way home from work hit a homeless man who had been beaten unconscious and left in the street by two vicious thugs in St. George, police said.

The 33-year-old victim was attacked by two men in their 20s near the Staten Island Ferry Terminal around 2:35 a.m., this morning, cops added.

He was left in the roadway at the corner of Richmond Terrace and Bay Street, where the unidentified cop was on his way home from work, police said.

“He leaves the ferry terminal and is assaulted by two males,” Police Commissioner Ray Kelly said. “An off-duty officer who was getting off of work struck him with his car he had to be removed from underneath the car by FDNY and ESU and was removed to SI Hospital in serious condition.”

The cop did not see the victim and struck him with his Ford Explorer but remained on the scene, called 911 and flagged down a patrol car, sources said.

The cop was not speeding or drinking.

The victim was taken to Richmond University Medical Center where his condition fluctuated between critical and stable condition.

“He has a fractured pelvis and femur,” Kellys added. “He’s known to the department as someone who frequents the ferry terminal.”

No arrests have been made.

“We have a description of two males who assaulted him,” Kelly said. “We’ll be putting that out as we get more information.”

kconley@nypost.com