A three-year-old boy is in critical condition after he was shot in the head this morning in a Flatbush apartment.

Cops say they were summoned to a second floor apartment at 520 East 21st Street in the Flatbush-Ditmas Park section of Brooklyn at 3:31 a.m., where shots had been heard a few minutes earlier. Officials say the injured toddler was struck on the left side of the head; he was transferred to Kings County Hospital, then Columbia-Presbyterian, and finally Weill-Cornell in critical condition.

He was reportedly in the apartment with a man and a female babysitter; officers say one person is currently in custody, though no arrests have been made. They are investigating whether the shot came from a stray bullet from outside that came through a window. The toddler had been bitten by a pit bull six months ago, according to neighbors.