More than 100 tenants at an apartment building in Hempstead were forced from their homes Wednesday due to dangerous levels of carbon monoxide.

Officials say the incident happened at an apartment building on Fulton Avenue just before 7:30 a.m. Officials say nine residents were taken to the hospital.

"Before I even hit the door, my meter was going off," says Kyle Boles, the assistant chief of the Hempstead Fire Department. "I found two residents in a back room passed out."

Twenty-two residents spent the day at the American Red Cross disaster shelter that's been set up at Kennedy Park in Hempstead. Red Cross officials say they are working with the Office of Emergency Management and social services to determine a recovery plan for the residents.

Village officials say it appears the landlord illegally installed heating units in all 15 apartments, without permits.

"The installation itself was not done professionally," says village trustee Waylyn Hobbs. "Because the pipes weren't connected right, it was able to emit CO gas throughout the building."

Village officials also learned that over the last few years the landlord has been charging tenants upward of $100 more for gas per month then what was agreed upon in their leases. They say an investigation and inspection would have been done if someone would have complained, and that maybe the illegal heating units would have been found.