A 76-year-old man shot by a state trooper inside his New Jersey home after a 911 call sent officers to the wrong address was fired upon first, a friend of the man said.

Gerald Sykes was in stable condition at a hospital in Camden with gunshot wounds after the shooting late Friday night in a largely rural area about 40 miles south of Philadelphia.

Richard Kaser, a family friend, said he visited Sykes in the hospital and spoke to family members.

Kaser said Sykes saw someone approaching his back door and thought it was an intruder. He said Sykes retrieved his shotgun and was standing inside the house when one of the troopers fired several times.

Sykes fired once with his shotgun, Kaser said, before falling down.

The state attorney general's office is investigating the shooting and declined comment Monday.

In a statement released Saturday, the office said the troopers first knocked on the front door at about 11:30 p.m. and, not getting an answer, went around to a back deck and shined flashlights through a glass door.

The statement described "an exchange of gunfire through the sliding glass door" in which the trooper fired four rounds and Sykes fired a single round. It didn't say who fired the first shot.

One of the troopers suffered a graze wound and was treated at a hospital and released.