FORT WORTH, Texas (AP) — Six people, five of them children, were hospitalized in critical condition after being exposed to carbon monoxide, apparently from a running vehicle at their home, according to fire officials in Fort Worth, Texas.

Fire Department spokesperson Craig Trojacek told local media at the scene that firefighters were called to the home about 8 p.m. Monday by a child who met firefighters at the door then collapsed after saying her mother was acting oddly.

A fire department spokesperson did not immediately return a phone call for comment Tuesday and the ages of the six were not immediately available.

The five children and one adult were taken to a hospital in critical condition and five firefighters who rushed into the home without protective gear to remove the occupants had elevated levels of carbon monoxide and were treated with oxygen.

Firefighters said the carbon monoxide appeared to have come from a vehicle with the engine running that was found in the garage of the home.