A 23-year-old woman died and another woman was critically injured when their car was t-boned by an off-duty cop who was allegedly drunk, police and sources told the Post.

The fatal crash happened just before 5 a.m. Sunday at the intersection of E. 55th Street and Foster Avenue in East Flatbush, according to police.

The 47-year-old police officer was driving a 2019 Nissan GTR east on Foster Avenue when he crashed, head-on into the side of a 2012 Mazda MZ6 — which police believe blew through a stop sign on E. 55th Street.

The Mazda — driven by a man who took off on foot after the crash — was sent spinning into a telephone pole, according to police.

The 23-year-old passenger in the Mazda was rushed to Brookdale Hospital, where she died, according to police. Her name was not released as cops have not told her family.

Another passenger in the same car, a 22-year-old woman, was taken to Kings County Hospital, where she was in serious but stable condition Sunday.

The cop, whose name was not released, was taken into custody on pending charges.

A high-ranking police source said the officer in the counter-terrorism bureau of the NYPD is expected to be charged with DWI.