Officials in the Quintana Roo state say that eight Americans are among those killed in a bus crash Tuesday in eastern Mexico.

Twelve people died after the tour bus they were riding in flipped over en route to Mayan ruins in the Yucatan Peninsula. Two Swedes and one Canadian were also confirmed dead, The Associated Press reports. A Mexican tour guide was also killed.

The U.S. State Department confirmed "multiple" U.S. citizens among the dead, as well as several injured. The AP reports that 20 people were hurt in the crash.

"We express our heartfelt condolences to all those affected by this tragedy," the U.S. Embassy in Mexico said in a statement. "We are in contact with local authorities, and will continue to monitor the situation. We have staff on the scene and at local hospitals to assist victims and loved ones."

The passengers were largely tourists from two Royal Caribbean cruise ships and were headed on an excursion to the Chacchoben ruins.

The local police chief had a possible explanation for the crash: the driver might have lost control of the bus after one of its tires exploded.

"It seems a front tire of the bus exploded, making it lose control and leave the asphalt," Carlos Briceno Villagomez, head of the police in the Bacalar municipality, told a Mexican TV network, accordingto Reuters.

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