The officers are being treated as suspects over Friday's incident, when a sport-utility vehicle with diplomatic plates was chased by four cars south of Mexico City and hit by a hail of bullets.

"The judge placed them under temporary detention for 40 days ... for abuse of power," a Mexican government official told AFP on condition of anonymity.

The official refused to list the charges that the officers could face over the shooting, which the US embassy has described as an ambush. The judge must decide the degree of responsibility of each suspect.

The officers will be transferred from one of the attorney general's regional offices in the state of Morelos to a provisional detention center in Mexico City.

The Mexican navy and public security ministry say the officers were hunting for criminals south of the capital when they shot at the diplomatic car. A Mexican navy captain traveling with the US employees was slightly injured.

The US government employees and the Mexican navy captain were heading to a military facility when a carload of gunmen chased and fired at them on a dirt road, the navy and public security ministry said in a statement.

When the US vehicle veered back onto a highway, three more cars joined the chase and shot at the SUV, which was riddled with bullets near Tres Marias, a town 50 kilometers (30 miles) south of the capital.

The US embassy has not identified the two employees wounded or the nature of their work in Mexico, which is in the throes of a drug war that has left 50,000 people dead since 2006.