Egyptian security forces opened fire on a caravan of tourist vehicles in the country’s Western Desert late Sunday night, killing at least 12 people visiting from Mexico and injuring 10 others, among them Mexican tourists and their Egyptian tour guides, officials said.

The tourists were mistakenly killed by a “joint force from the police and armed forces” who were pursuing “terrorist elements” in an area of the desert, according to a brief statement posted to the official Facebook page of Egypt’s Ministry of Interior. The episode happened around midnight, security officials said.

“The incident resulted in the deaths of 12 people and the injury of 10 people from among the Mexicans and the Egyptians,” the statement said. “They have been taken to hospitals for treatment.”

The security forces said that they had believed that the vehicles were being used to transport terrorists. The statement said the group had been driving in a restricted area where unauthorized access is banned.