A cop fatally shot a pit bull Friday night after the dog bit his partner in the stomach in the hallway of a Manhattan housing project, police said.

The two cops were responding to a report of a domestic assault on the 10th floor of a building in the Lillian Wald Houses on Avenue D at about 9:30 p.m. when someone opened an apartment door and the dog came charging out.

The injured officer was taken to Bellevue Hospital, where he is in stable condition.

One man is in custody in connection with the domestic assault, cops said.