James Reynolds: The mid-morning explosion started a fire destroying more than 30 houses

At least 30 houses were reported to have been destroyed by the blast and subsequent fire in the small village of Arroyo de Piedra near Sabanalarga on the Atlantic coast about 400 miles (650 km) north of the capital, Bogota.

State health officials said nine people were killed immediately and three died later in hospitals nearby.

Three of the dead and six of the wounded were children, they said.

Officials fear the death toll could rise, as burn victims succumb to their injuries.

"The explosion was so large it sent rocks flying and brought down power and telephone lines," said Rafael Bohorquez, a local health official interviewed on Colombian radio.

"The nearby houses caught fire and their inhabitants have lost nearly everything," he said.

It is not yet clear what caused the explosion of the gas pipe, which runs directly under the town, but firefighters say it was accidental.

BBC South America Correspondent James Reynolds says the official cause of the blast will not be established until an investigation is carried out by the company which runs the pipeline.

James Reynolds: Second pipeline explosion in as many months

It is the second time in recent months that a pipeline explosion in Colombia has resulted in deaths.