A carbon monoxide leak in a Newark senior apartments complex resulted in 11 people being hospitalized on Saturday, public safety officials said.

Police arrived shortly before 6 a.m. Saturday at the Stephen Crane Senior Citizen building in response to a call that two people had passed out, Public Safety Director Fritz Fragé said in an email.

Eleven people were taken from the scene to local hospitals, showing signs of shortness of breath and lightheadedness, officials said. Five were taken to University Hospital, and the remaining six to Clara Maas Medical Center. All are currently in stable condition. Their ages were not available.

The building is managed by the Newark Housing Authority. Firefighters on the scene found a furnace to be emitting carbon monoxide and shut it off, per officials.

“Carbon monoxide readings are down to ‘0’ per the Newark Fire Department,” the housing authority stated in a Facebook post shortly after 10 a.m. “Fire department will let residents back in once the system is tested.”