Alvarado, TX – The lighting of a cigarette inside a travel trailer with an undetected propane leak apparently sparked an explosion late Tuesday in Alvarado that injured four people, including two children, Johnson County Sheriff’s officials said Wednesday.

The victims, who suffered serious burns, were taken by helicopter ambulance to locals hospitals for treatment. Their conditions were unknown Wednesday morning.

Lt. Tim Jones, a spokesman with the Johnson County Sheriff’s Office, said the four burn victims — a man, a woman, and what is believed to be the woman’s two young children — had been inside thetrailer when the fire and explosion occurred about 11 p.m. at the Dodge City RV Park in the 4100 block of County Road 616.

One of the victims told emergency responders that the roof immediately turned blue with flames after a cigarette was lit inside the trailer, Jones said.

Jones said investigators believe the fire and explosion started due to a leak in a propane tank mounted on the trailer’s front tow hitch.

Lillian and Mansfield fire departments were also dispatched to the scene.