A New York City police officer testifying in his own defense got choked up while describing the moment he realized a man had been shot in a dark housing project stairwell in 2014.

Peter Liang left the witness stand for about a minute to compose himself before resuming testimony Monday.

Liang says he was startled by a noise as he opened the stairwell door in the Brooklyn complex, and his gun went off accidentally.

He says he went to look for the bullet and that’s when he discovered Akai Gurley’s girlfriend leaning over him.

Liang recalls saying, “Oh, my God, someone’s hit!”

Liang says he called for an ambulance but was also “shocked” and “panicking.”

Liang began his testimony by describing what are called “vertical patrols” in stairwells. He noted that public housing stairways can be sites of crime and danger.

Liang and his partner were patrolling a darkened stairway in a Brooklyn housing complex when Liang fired. The bullet ricocheted and hit Gurley a flight below.

Liang’s lawyers say the shooting was an accident, not a crime.

Prosecutors say Liang handled his weapon recklessly and did nearly nothing to help Gurley after realizing what had happened.

(AP)