An explosion ripped through a gas station in the eastern city of Santiago, injuring 31 people, including five seriously, Cuban state media reported Wednesday.

The blast happened Tuesday evening when the driver of a government-operated truck struck a gas tank, which tipped over and spilled its contents, the Sierra Maestra newspaper said on its website.

"Even as firefighters urgently tried to contain the spill, specialists agree that among a group of people nearby, a spark originated that ignited the spill and the fire extended to the tanks, causing the explosion," Sierra Maestra said.

State television broadcast images of a completely charred gas station, but the blaze was extinguished before it could spread to other buildings.

The victims were taken to a burn unit at a nearby hospital, and five were in "very grave condition," Sierra Maestra added.

Authorities were investigating.