Federal police in Mexico shot and wounded two US Embassy employees in a vehicle travelling south of Mexico city on Friday.
The Mexican Navy said the US personnel were on a main road to the city of Cuernavaca when the incident happened.
Details are still unclear, but the navy said the vehicle was fleeing from gunmen in another car.
in a statement, the public security ministry said the embassy personnel and a Mexican naval officer were going to a military installation when gunmen opened fire and chased them.
The BBC reports the wounded men are now in hospital. One was hit in the leg and the other in the stomach and hand.
Last year a US Immigration & Customs Enforcement agent was killed on a Mexican highway. Another agent was wounded.