Two U.S. Immigration and Customs Enforcement agents were shot in the line of duty today approximately 100 miles outside Mexico City Tuesday.
One of the officers has died from his wounds, reports the Associated Press, quoting an anonymous official.
A U.S. Embassy spokesman in Mexico City tells CBS News the two agents were shot while driving from Mexico City to Monterey by unknown assailants.
"ICE is working with the U.S. State Department, Mexican authorities and other U.S. law enforcement partners to investigate the shooting. Our thoughts and prayers are with our colleagues," ICE officials said in a statement this afternoon.
Homeland Security Chief Janet Napolitano condemned the attacks.
"Let me be clear: any act of violence against our ICE personnel - or any DHS personnel - is an attack against all those who serve our nation and put their lives at risk for our safety," Napolitano said. "We remain committed in our broader support for Mexico's efforts to combat violence within its borders."
The two agents were driving in the northern state of San Luis Potosi when they were stopped at what appeared to be a military checkpoint, said one Mexican official, who could not be named because he was not authorized to speak publicly about the case.
After they stopped, someone opened fire on them, the official said.
San Luis Potosi police said gunmen attacked two people a blue Suburban on Highway 57 between Mexico City and Monterrey, near the town of Santa Maria Del Rio, at about 2:30 p.m.
Police said one person was killed and another was flown to a Mexico City hospital, though they couldn't confirm the victims were the ICE agents.
Mexican Ambassador to the U.S. Arturo Sarukhan spoke with ICE chief John Morton to express Mexico's condolences, according to a spokesman.
"This is a difficult time for ICE and especially for the families and loved ones of our agents. Our hearts and prayers go out to them. This tragedy is a stark reminder of the risks confronted and the sacrifices made by our men and women every day," Morton said in a statement.
Though Mexico is seeing record rates of violence from warring drug cartels and a crackdown on organized crime, it is rare for U.S. officials to be attacked. The U.S. government, however, has become increasingly concerned about the safety of its employees in Mexico amid the escalating violence.
In March, a U.S. employee of a consulate, her husband and a Mexican tied to the American consulate were killed when drug gang members fired on their cars as they left a children's party in Ciudad Juarez, the city across from El Paso, Texas.
The U.S. State Department has taken several measures over the past year to protect consulate employees and their families. It has at times authorized the departure of relatives of U.S. government employees in northern Mexican cities.
In July, it temporarily closed the consulate in Ciudad Juarez after receiving unspecified threats.
In a famous case, in 1985 U.S. Drug Enforcement Administration agent Enrique "Kiki" Camarena Salazar was tortured and killed in Mexico. Mexican trafficker Rafael Caro Quintero is serving a 40-year prison term for Camarena's slaying.
ICE, the investigative arm of the U.S. Department of Homeland Security and the second largest investigative agency in the federal government, enforced immigration laws and is primarily responsible for arresting, detaining and deporting people who are in the U.S. illegally. It also investigates drug cases in the U.S. and Mexico and other types of trafficking.
It was created in 2003 through a merger of the investigative and interior enforcement elements of the U.S. Customs Service and the Immigration and Naturalization Service and has more than 20,000 employees in offices in all 50 states and 47 foreign countries.In December, U.S. Border Patrol agent Brian A. Terry was shot and killed just north of the Arizona-Mexico as he tried to catch bandits suspected of targeting illegal immigrants.
As CBS News reported last week, violence has been escalating in Mexican border towns. In Juarez, Mexico, nearly seven people a day have died this year.
Nationwide, almost 35,000 people have been killed in drug violence since President Felipe Calderon launched a military crackdown against drug trafficking shortly after taking office in December 2006.