PITTSBURGH — Six people at a home in Pittsburgh were sickened this morning by carbon monoxide.

Emergency crews and utility workers responded to the home about 3 a.m. after the residents reported feeling ill. They were taken to Allegheny General Hospital in Pittsburgh and are expected to recover.

Workers found high levels of carbon monoxide in the home, but it's not clear what caused it. Crews checked neighboring homes and didn't find any problems there.

Officials did not say how long it might take to find and fix the source of the poisonous gas.