Two U.S. Embassy employees were shot at and wounded by Mexican police on Friday after they were caught up in a police chase on the outskirts of the capital, Mexico's Navy said.

Police fired on the vehicle in which the embassy employees were traveling, which carried diplomatic plates, after the driver veered out of the way when he saw the officers' weapons.

"At that moment those in the ... (police) vehicle opened fire on the diplomatic vehicle," the Navy said in a statement. "Moments later, three other vehicles joined the chase and fired shots at the U.S. Embassy vehicle."

Two employees were taken to a hospital for treatment and their injuries were not life-threatening, it said. The U.S. government said the two employees were in stable condition.

The U.S. Embassy in Mexico said in a statement that the diplomatic vehicle was "ambushed by a group of individuals" and "sustained heavy damage" as a result of the attack.

Speaking on condition of anonymity, a Mexican government security official said federal police had thought the vehicle belonged to a group of suspected kidnappers they were pursuing, and opened fire on it.

"This was all because of a mix-up," the official said.

The Navy said the officers involved were being questioned.

"We are working with Mexican authorities to investigate an incident this morning in which two employees of our embassy in Mexico City came under attack by unknown assailants," said State Department spokesperson Victoria Nuland. "They are receiving appropriate medical care and are in stable condition."

The incident took place on a highway on the southern outskirts of Mexico City close to the city of Cuernavaca, which has been ravaged by criminal gangs during the government's conflict with drug cartels.

The U.S. Embassy said it has been "cooperating closely" with the investigation initiated by Mexican authorities.

Roadside shootings have been a feature of the violence linked to drug gangs that has overshadowed President Felipe Calderon's six years in office. Gangs have been known to set up fake military checkpoints to ambush rival groups.

Last year, two U.S. Immigration and Customs Enforcement agents were shot by hitmen on a major Mexican highway. One of the agents died.