Mexican President Claudia Sheinbaum Pardo said Monday she wants answers, calling it an issue of "sovereignty," after two U.S. embassy personnel died in a car accident following a drug raid that she was unaware of in northern Mexico.

"We weren't aware that there would be a direct operation between the state of Chihuahua and personnel from the U.S. Embassy to Mexico. So we’re asking for all the information from the government of Chihuahua and also from the United States and reviewing if there was a violation of national security law," Sheinbaum said April 20 during her daily news conference. "We’re clear and we’ve come to expect that there’s collaboration and coordination but not joint operations on the ground."

The Mexican president’s comments come after authorities in the state of Chihuahua announced April 19 that the U.S. officials died along with the director of the state’s investigative agency and an agency officer following an "operation to destroy clandestine laboratories" near the border with the state of Sinaloa.

In a later statement, authorities in Chihuahua said the Americans did not have a role in the operation and were only in the car incidentally.

According to the Chihuahua prosecutor’s office, Mexican authorities returning from the raid passed through a community where the Americans were giving drone flying lessons and the U.S. officials asked to ride in the government convoy to get to another location.