A U.S. Immigration and Customs Enforcement agent has been killed and another shot in the arm and leg during an attack in Mexico.
ICE, as the agency is known, issued statements saying the two were shot "in the line of duty" Tuesday afternoon while driving between Mexico City and the northern industrial city of Monterrey.
Mexican officials say they stopped at what seemed to be a military checkpoint, possibly set up by drug traffickers, as the military says it had no checkpoints in that area.
Homeland Security Secretary Janet Napolitano issued a statement saying she is "deeply saddened" by the incident and pledging the full support of her department to the Mexican authorities who are investigating. She said the United States remains committed to Mexico's efforts to combat violence within its borders.
Attacks on U.S. law enforcement in Mexico are rare, despite increasing U.S. contributions to Mexico's fight against drug trafficking. The last high-profile attack on a U.S. officer was in 1985, when a Drug Enforcement Administration officer was captured, tortured, and killed while on assignment there.
Mexican military forces have been engaged in a brutal struggle against violent drug cartels. At least 34,000 people have been killed in Mexico's drug war since President Felipe Calderon took office in late 2006 and began cracking down on the cartels.
Some information for this report was provided by AP, AFP and Reuters.