An unidentified woman was found dead “lying in a pool of blood” inside a Brooklyn building Saturday, cops and sources told The Post.

The victim was discovered inside 113 Thatford Ave., in Brownsville around 11:30 a.m. where EMS pronounced her dead, the NYPD said.

Police found the woman “lying in a pool of blood” while investigators recovered three shell casings, law enforcement sources said.

“The investigation is ongoing,” a department spokesperson said.

Stunned neighbors were not sure what had transpired.

“You gotta talk to the cops. We don’t know,” said one.

“It s sad. I feel for that family,” added another, who was sitting on the stoop next door smoking a cigarette.

Tight-lipped investigators could be seen going in and out of a ground-floor apartment on Saturday afternoon.

The multi-family dwelling was built in 2007, according to public records.

This is a developing story.