At least seven people were killed and another three injured when a small plane crashed in southwestern Colombia on Sunday, a firefighter said.

"Nine people were on board the plane. Seven died, while two are seriously injured," said Juan Carlos Ganan, the commander of firefighters in the area.

The third person injured was a child on the ground in the area where the plane crashed, Ganan said.

Firefighters were trying to stop fuel leaking from the aircraft, Ganan added.

The plane, which crashed at 14:11 (19:11 GMT), was headed from Popayan to Lopez de Micay, both in Cauca department.

The cause of the crash was not known and an investigation was under way, Ganan said.