Police were investigating Monday after they said a 3-year-old boy with bruises died at a Brooklyn hospital after two people dropped him off and fled, according to the NYPD.

Department officials said officers responded to a 911 call around 11:30 a.m. Sunday and found the boy unresponsive at the SUNY Downstate Medical Center in East Flatbush. Hospital staff told them that two unidentified individuals had left him there before driving away, police said.

The boy was pronounced dead at the hospital. His identity has not been released and the city’s chief medical examiner’s office was working to determine his cause of death.

Officials said they were looking into the relationship between the boy and the two people, as well as the kind of car they were using. Police have not announced any arrests in the case.

SUNY Downstate declined to comment through a spokesperson, who pointed to the NYPD for questions about the investigation.

This story has been updated with additional information.