Five people were taken to the hospital for possible carbon monoxide poisoning Saturday after a CO alarm went off at an East Harlem building, officials said.

The alarm sounded around 10:30 a.m. on the top floor of a six-story apartment building at 245 East 110th St., an FDNY spokesman said.

The five people were taken to Weill Cornell Medical Center. There was no immediate word on their conditions.

One first responder radio broadcast said FDNY reported CO readings “in the high 400s.”

A mid-level CO reading is considered between 51 ppm and 100 ppm, while 101 ppm is considered dangerous if someone is experiencing symptoms.