At least 12 killed in Mexico bus accident

At least 12 people died when a bus carrying cruise ship passengers to Mayan ruins in eastern Mexico flipped over on a highway on Tuesday.

Seven Americans and two Swedes were among the injured, Quintana Roo state Civil Defense spokesman Vicente Martin said. 

He said authorities hadn't yet established the nationalities of the dead.

Video images from the scene showed the bus on its side in vegetation off the two-lane highway, with some survivors lying on the pavement and others walking around.

Miami-based Royal Caribbean Cruises said in a statement that passengers from two of its ships, the Celebrity Equinox and Serenade of the Seas, were involved in the crash. 

Investigators were working to determine the cause of the crash, which occurred as the bus was on its way to the ruins at Chacchoben, about 175 kilometers south of Tulum.

Chris Brawley, a passenger on the Serenade of Seas, was on a bus headed to the same Mayan ruins when they came on the scene minutes after the accident.

Brawly said he didn't see any sign of any other vehicle being involved in the crash, which happened on a narrow, two-lane road with no shoulder or guardrail.

He said he did not see the crash, but "the bus clearly lost control somehow as there were swerve marks all over the road surface."

Costa Maya Mahahual, the bus company involved, said in a statement that in addition to the tourists, a guide and driver were aboard the bus.