A 34 year old Carstairs man is in Foothills Hospital with severe burns after a propane explosion at a Water Valley campground.

It's still not clear what caused the explosion which left the man with burns covering more than half of his body.

Amateur video showed the propane explosion, creating a fireball that consumed the entire campsite including an RV.

Jessica Arnatt and her family were in another campsite just 20 metres from the flames. At first she heard a loud, dangerous, hissing sound.

"I was watching it happen," says Arnatt. "The explosion came out one side (of the tank), and then out of the other side. It then went straight up and it was as tall as the trees."

Even as the flames raged, Michael Luyendyk and a friend rushed to the scene.

They frantically searched for the man's young son, and removed all other propane tanks from the site.

"We were trying to get all of the propane tanks out," says Luyendyk. "They had a quad with a gas tank on the back and it started melting so we pulled that out. Our adrenalin kicked in, and it was heavy, but I said we have to get this out of here."

Arnatt says while attempting to control the flames, the victim caught fire and jumped into the nearby river.

Early results from the investigation suggest the man was trying to fix a propane barbeque. A hose became disconnected, and the escaping gas was ignited by the nearby campfire.

Emma Upshaw was nearly 100 metres from the campsite. Even from that distance, she could here all the commotion

"We heard a whooshing sound, then a huge bang and then a bunch of people screaming," says Upshaw. "It sounded like a truck tire was exploding, but it just went on and on."

Luyendyk says the situation could have been much worse if the campground had been drier.

"Two hours before we came into camp, we had the rain and hail," says Luyendyk. "It soaked everything."

RCMP say the man's burns are serious but not life threatening.