Mexican officials revealed that four foreigners — not two — were present during a counterdrug operation in northern Mexico where a crash killed two men later identified as C.I.A. officers.

The two Americans were killed on Sunday when their vehicle crashed while returning from an antidrug operation led by Mexico’s armed forces in the state of Chihuahua.

The deaths of two C.I.A. officers in a crash in northern Mexico sparked questions about authorization and sovereignty, but also reflected a longstanding, sensitive security partnership between the two countries.

The two Americans were killed on Sunday when their vehicle crashed while returning from a counter-cartel operation led by Mexico’s armed forces in the state of Chihuahua.