A pit bull badly mauled a 2-month-old boy and seriously injured his mother on Long Island, according to a report.

The 36-year-old woman was carrying the baby in a car seat about 12 p.m. Thursday when she knocked on an apartment door in Elmont where the dog and another pit bull lived, Newsday reported.

“As soon as the occupant of the residence opened the door, the two pit bulls rushed out of the door,” Nassau County police Detective Lt. Richard LeBrun said.

“One pit bull is a 4-year-old male. That pit bull now attacked the mother, inflicting a very, very serious leg wound. The pit bull then went to the 2-month-old child, who’s in that baby seat, and did bite that child in the head and facial area,” he said.

The child was listed in critical condition at Cohen Children’s Medical Center in New Hyde Park, where he underwent surgery for a cranial injury, officials said.

His mother also was hospitalized with leg injuries.

Three workers performing home renovations next door ran to help the victims. One of them punched the dog in the face and pulled it off the child, LeBrun said.

Another worker put the woman and her son inside a vehicle for safety, police said.

The vicious pooch was taken to the Hempstead Town animal shelter along with the other dog, which did not attack the unidentified victims, LeBrun said.

Neighbor Hassan Mahmood said he’s afraid of the dogs because they go berserk when they see people and other pets.

“When they see somebody, they just go nuts,” Mahmood told Newsday. “I don’t get out of the car when I see them.”