Two men were killed in separate Brooklyn shootings on Monday – one in a public housing stairwell and the other in front of a deli, authorities said. 

A 37-year-old man was discovered unconscious and bleeding around 11 p.m. in the first-floor stairwell of a building on Batchelder Street near Avenue X, part of NYCHA’s Nostrand Houses in Sheepshead Bay, cops said. 

He had suffered a gunshot wound to the head and was pronounced dead at the scene, cops said. 

The victim was not immediately identified pending family notification, and no arrests have been made. The motive is unclear.

Hours earlier, Dion Reid, 26, was blasted in the torso and ankle in broad daylight outside the Francena Mini Market on Sterling Place near Buffalo Avenue in Crown Heights, cops said. 

Reid — who lived just blocks from the scene – was rushed to the Kings County Hospital Center, where he was pronounced dead. 

The circumstances leading to that shooting remained unclear Tuesday.