A man was shot dead in a Brownsville apartment building this afternoon, police said.

Cops responding to a 911 of a shooting at 204 Lott Ave. in Brooklyn found a 37-year-old man “unconscious and unresponsive with an apparent gunshot wound to the chest,” police said.

The victim, identified as Omar Murray, was loudly quarreling with another man in a hallway when suddenly four shots rang out, sources said.

Murray’s wife, who was in the apartment, called 911, sources said.

Murray was taken to Brookdale Hospital and pronounced dead on arrival.