A bus carrying cruise ship passengers on a tour of ancient Mayan ruins flipped on a highway in southeast Mexico early Tuesday, killing at least 12 people and injuring 18 .

The fatalities include five Americans, four Canadians, two Swedes and one Mexican, ABC News reported, citing an unidentified official familiar with the investigation.

Authorities confirmed to Reuters that a child was among the dead. A South Florida family told the Sun Sentinel they believed an 11-year-old boy and his grandmother were killed.