Police on Monday pleaded for public help in finding a man whose gunfire hit an 8-year-old boy in the head as he lay in bed in the Del Rey section of Los Angeles.

Capt. Nicole Alberta Carranza said at an afternoon news conference that investigators are looking for anyone who may have seen the unknown suspect coming or going from the house or may have a description of his vehicle.

Family members say they don’t know who the man was.

Police say the man in a hooded sweatshirt came into the house in the 11000 block of Wagner Street through unlocked doors shortly before midnight Sunday.

“The father was transferring his 8-year-old from his bedroom into his child’s bedroom when he heard the front door open,’’ LAPD Sgt. Frank Preciado said. “At that point, he assumed it was his 20-year-old son.’’

Instead, the resident was confronted by the gunman, who had walked in through the unlocked door. The suspect got into an argument with the father and began pursuing him through the house, firing about 10 shots, some of which penetrated the wall of the boy’s bedroom, police said.

“He was saying, ‘I’ve got children in my room,’ ’’ Preciado said. “It was heart-wrenching. We don’t know exactly what transpired between these two adults, but the children actually were innocent.’’

The boy was in bed in an adjacent room behind a partial wall, and the bullet that struck him may have gone through the wall or hit him directly.

The father told detectives the suspect, whose face was obscured by some kind of covering, fled after the shooting. It wasn’t known if he left on foot or in a car.

The boy was treated and taken to the hospital, where he underwent surgery and was reported in critical but stable condition.

Officers shut down the street in front of the house as they searched for the gunman in the residential neighborhood near Venice Beach.

No other family members were injured. The young victim’s 17-year-old brother also was in the bedroom at the time of the shooting. The victim’s mother and grandmother were in another room.

The family had left the front door unlocked because they were expecting the 20-year-old son to come home, according to Officer Sara Faden.