Mexican President Claudia Sheinbaum said Tuesday her government is investigating potential violations of national security after a car driving in the mountains of Chihuahua carrying two Mexican law enforcement officials and two U.S. CIA agents on Sunday fell into a ravine and exploded, killing all four passengers. The crash followed an operation to destroy a large drug lab in a rural area, but Sheinbaum says she was unaware of any American involvement and added that joint collaborations between the local government and the U.S. without federal permission would be a violation of Mexican law. Chihuahua's attorney general has denied that Americans were involved on the ground in the operation. CBS News' explains what happened #news #mexico #US #CIA #cartel