A rookie police officer fatally shot an unarmed man late Thursday in a "pitch black" Pink Houses stairwell as his girlfriend, whom he had been visiting, watched in horror, officials and a witness said.

Officer Peter Liang, who had been on the job fewer than 18 months, had his flashlight and gun out when the weapon "accidentally discharged," hitting Akai Gurley who was "a total innocent," NYPD Commissioner Bill Bratton said.