Though the deceased have not been identified, the bus was carrying seven Americans and two Swedish citizens, the Associated Press quoted Quintana Roo state civil defense spokesman Vicente Martin as saying.

According to government officials, the bus was carrying 31 passengers, 18 of whom suffered injuries.

Among the 12 deceased, one was a minor girl.

"The bus belonging to the company Turismo de Aventura carried 31 passengers, of which 12 people unfortunately died, among them, a minor, 18 injured are reported, who have been channeled and treated in hospitals in the area," the statement read.

The commuters were heading towards the Chacchoben site, 177 kilometres (110 miles) south of Tulum, famous for its Mayan ruins.

Condoling the loss, a US Embassy spokesperson said, "We express our condolences to all those affected by this tragedy."

The cause of the accident is presently being investigated.

Image: Screengrab from YouTube