Rio Grande County, CO- At least 13 people were injured, seven of them airlifted to Denver, after a home under construction exploded in the town of South Fork Tuesday afternoon.

The Colorado State Patrol says the explosion happened around 1:10 p.m.

South Fork is west of Alamosa.

The South Fork Fire Department says workers were remodeling the home when a propane space heater started leaking gas into the basement. When they lit one of the space heaters in the house, it caused the gas to explode.

The fire department says 13 people were hurt by the explosion.

Flight for Life and Airlife Denver helped in transporting seven of the victims to hospitals: University Hospital, St. Anthony Central and Swedish Hospital.

Other, non-critical patients were brought to Rio Grande Hospital in Del Norte.

None of the victims’ conditions were released.

Some of the injured may be friends of the homeowners, who were not at home at the time of the explosion. The other victims were construction workers.

The explosion happened in the River Green subdivision.

South Fork Fire says the blast destroyed the home and damaged the garage.

9NEWS talked to a construction worker who was two doors away from the explosion. He wanted to remain anonymous but told us he believed there were eight to nine people inside the home at the time of the explosion putting up drywall.

He told us, “There’s nothing left but the roof.”

The witness says he saw around seven people injured, many of them with severe burns.

Firefighters and ambulance crews from South Fork, Del Norte and Monte Vista all responded to the destroyed home.