One emergency medical technician staffer has died and three co-workers are hospitalized after all were overcome by carbon monoxide while in duty in east Texas.

A spokeswoman at Good Shepherd Medical Center in Longview, which operates Champion EMS in White Oak, says the victims were discovered Friday morning by other workers during shift change.

Victoria Ashworth told The Associated Press that the carbon monoxide apparently was from a generator on an ambulance. She had no further immediate details on the source.

Ashworth says a female EMT student was pronounced dead after being transported to the hospital. Ashworth says a paramedic and two emergency medical technicians, all male, are in good condition. Their names were not immediately released.

White Oak is located 115 miles east of Dallas.