A woman was found dead, lying face-down in the hallway of a Brooklyn building Sunday evening, cops said.

A resident discovered the unresponsive woman around 7:30 p.m. on the third floor of the building on Marcy Avenue near South Ninth Street in South Williamsburg, police said. 

EMS workers found a bruise on the woman’s forehead, authorities said. 

She was rushed to Woodhull Medical Center, where she was pronounced dead. 

The circumstances of her death were unclear Monday morning. 

The woman, 37, whose name was not immediately released, did not live in the building where she was discovered.