An armored U.S. Embassy vehicle is seen riddled with bullets, most concentrated around the passenger-side window, after it was pursued in a high-speed chase and shot at by Mexican federal police officers in the mountains south of Mexico City on Friday, Aug. 24. Two U.S. government employees were shot and wounded, a law enforcement official said. (Alexandre Meneghini/AP)

The Mexican attorney general announced Monday that 12 Mexican federal police were taken into custody for their involvement in the shooting of two U.S. government workers who were wounded last week on their way to a Mexican Navy training camp.

The Mexican police officers have not been formally charged, but may be held for 40 days for questioning about possible crimes that include attempted murder, aggravated assault, damage to property and abuse of authority.

A pair of U.S. government employees, traveling in an armored U.S. Embassy sport-utility vehicle with diplomatic license plates, were pursued in a high-speed chase and shot at by Mexican federal police officers in the mountains south of Mexico City on Friday morning.

Photographs of the U.S. government Toyota Land Cruiser show it riddled with bullet holes, with a tight concentration of rounds striking but not penetrating the passenger’s side window at head level, suggesting the assailants tried to kill whoever was inside.

The U.S. government has not released the names of the two wounded Americans or which U.S. agency they worked for.

Over the weekend, the two men, both in stable medical condition, were evacuated to the United States, according to a U.S. State Department official.

One of the wounded men was attached to the U.S. Embassy in Mexico City, the other appeared to be in Mexico on temporary assignment, according to U.S. law enforcement officials who spoke the condition of anonymity because the case is still under investigation.

The case is an embarrassment for both Mexican and U.S. officials. The U.S. government has committed more than $1.6 billion in aid to training Mexican police and soldiers and arming them with Black Hawk helicopters, surveillance and listening devices and intelligence generated by flyovers by U.S. drones.

The two U.S. employees were headed to a Mexican Navy training facility, accompanied by a Mexican Navy captain, meaning that U.S. trainers were attacked by the federal police forces they have spent the past five years helping to train.

Families of the arrested officers have told the Mexican media that their relatives either opened fire in confusion or were not involved.

A lawyer for three of the Mexican police officers, Enrique “Rusty” Mondragon, said his clients didn’t shoot at the Americans.

They were chasing a carload of kidnappers in the area, the lawyer said. “They did shoot at the kidnappers,” Mondragon added, but said it was only after that exchange that his clients were called for backup to chase the vehicle that contained the two Americans.

Rep. Henry Cuellar (D-Tex.) said the U.S. government should continue to spend aid money training Mexican police.

“This transformation is going to take years,” he said. “And no matter how much training you have, you can still have a few bad apples.”