A pit bull mauled its owner to death inside a Bronx apartment building early Friday — before responding cops fatally gunned down the vicious dog, authorities said.

THE BRONX - A 41-year-old man was killed by his own pit bull in the Bronx, the NYPD said. Police responded on Friday just after 3 a.m. to an apartment building on Simpson Street in the Longwood section. According to police, the man was on the floor with the animal clamped down on his throat when officers arrived.