Fire engulfed a five-story apartment building in New York City early Monday and left nine people, including three police officers, injured, officials said.

The blaze occurred at an East Harlem apartment in upper Manhattan. At least one of the three police officers injured in the fire suffered serious injuries, but they weren’t considered life-threatening, the New York Post reported. Seven people suffered minor injuries.

The fire broke out around 2 a.m. and was under control about 30 minutes later, according to New York's WNBC-TV reported. Responding officers were reportedly banging on doors to warn residents about the fire.

The cause of the fire was under investigation.

A dozen New York City Fire Department units, comprising about 60 firefighters, responded to the blaze, the Post reported.