PHILADELPHIA — Investigators believe a gasoline-powered generator running a fan for inflatable playhouses produced carbon monoxide at a child's birthday party, sending 17 people to a hospital.

Children were playing in two large Moonbounce balloon playhouses that were being kept inflated by the fan, Fire Department Capt. John Cleary said Sunday.

Six of those sickened at Saturday's party were ages 3 to 16.

None of the injuries was considered life threatening.

Most of those who were sickened were expected to be released Sunday, Cleary said. Two children were being treated in a hyperbaric chamber.

The incident happened inside the H & H Community Development Center.

Although the investigation was still under way, officials believe the generator was to blame, Cleary said.