Fifteen people are unaccounted for after a series of explosions at a gas plant in the U.S. state of Florida, BBC News reported.

Between 24 and 26 people were working at the Blue Rhino Propane Plant, in the central town of Tavares, when the blasts began at about 23:00 (03:00 GMT), blowing the roof off. The explosions continued for about an hour and caused a large fire.

At least seven people were injured and several have been flown to nearby hospitals. Another two escaped unhurt.

People living within 0.5 miles (0.8km) of the plant have been evacuated.

However, a spokesman for the Lake County Sheriff's office said emergency crews believed the fire had been contained and that there was no immediate danger to Tavares residents.

The cause of the initial explosion is not yet clear.

Former plant supervisor Don Ingram told WESH-TV that Blue Rhino took in propane tanks used for home barbecues, cleaned them, checked their valves and then refilled them.

About 4,000 to 5,000 tanks were refilled each night and were stacked on plastic pallets four or five high behind the filling station, Ingram said.