Mexican City, Mexico - Four people, including two US embassy workers and two Mexican law enforcement agents, were killed in a car accident while returning from a drug raid in northern Mexico.

On Friday and Saturday, six clandestine synthetic drug labs were raided in Morelos, a town located in Mexico's northern state of Chihuahua, Mexican prosecutor Cesar Jauregui told reporters on Sunday.

The raids followed three months of planning and investigating, and saw law enforcement agents seize narcotics and destroy infrastructure designed to manufacture drugs.

The tragic incident occurred when a vehicle skidded off the road and plunged into a deep ravine, Jauregui confirmed to reporters.

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The US embassy staff killed in the incident were "instructor officers" who "were carrying out training tasks" as part of an anti-drug cooperation between the US and Mexico.

US ambassador Ronald Johnson paid tribute to the victims in a post to X and identified the two Mexican officers killed in the crash as the Director of Chihuahua's State Investigation Agency and an officer within that agency.

"We are deeply saddened by the tragic loss of two US Embassy personnel, the Director of Chihuahua’s State Investigation Agency (AEI), and an AEI officer in this accident," Johnson wrote on Sunday.

"We honor their dedication and tireless efforts to confront one of the greatest challenges of our time," he continued. "Our thoughts and prayers are with them and their loved ones."

"This tragedy is a solemn reminder of the risks faced by those Mexican and US officials who are dedicated to protecting our communities."