A U.S. Immigration and Customs Enforcement agent was killed and another wounded while driving through northern Mexico Tuesday, in a rare attack on American officials in this country which is fighting powerful drug cartels.
Homeland Security Secretary Janet Napolitano said one agent was critically wounded in the attack and died from his injuries. The second agent was shot in the arm and leg and remains in stable condition.
ICE Director John Morton late Tuesday identified the slain agent as Jaime Zapata, who was on assignment from the office in Laredo, Texas, where he served on the Human Smuggling and Trafficking Unit as well as the Border Enforcement Security Task Force. The injured agent, who was not identified, remains in stable condition, Morton said.
"I'm deeply saddened by the news that earlier today, two U.S. Immigration and Customs Enforcement (ICE) special agents assigned to the ICE Attache office in Mexico City were shot in the line of duty while driving between Mexico City and Monterrey by unknown assailants," Napolitano said.
U.S. and Mexican officials said they were working closely together to investigate the shooting and find those responsible. They did not give a motive for the attack.
"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 may have 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. Mexican military officials said they have no checkpoints in the area.
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.
A U.S. law enforcement source who was not authorized to speak on the case said the agent who died was on loan from Laredo, Texas.
Mexican Ambassador to the U.S. Arturo Sarukhan spoke with Morton to express Mexico's condolences, according to a spokesman.
"Please keep Special Agent Zapata's family, friends, and colleagues close to your heart during this difficult time. May the work we continue to do as an agency be worthy of a sacrifice as great as the one made by Special Agent Zapata," Morton said in a statement Wednesday.
Zapata, who joined ICE in 2006, had also served as a member of the U.S. Border Patrol in Yuma, Arizona. He was a native of Brownsville, Texas and graduated from the University of Texas at Brownsville in 2005. No age was given for Zapata.
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 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.
Mexico is fighting heavily armed and powerful drug cartels that supply the U.S. market. Since President Felipe Calderon launched a military crackdown against drug trafficking shortly after taking office in December 2006, almost 35,000 people have been killed in drug-related violence.
Fox News' Mike Levine and the Associated Press contributed to this report