Investigators continue to search on the ground and in the air for the drug traffickers suspected of killing a U.S. border patrol agent in southern Arizona yesterday.
The slain agent was married father-of-two, Nicholas Ivie.
ABC News said his wounded partner was not immediately identified, and a third officer was unharmed in the shooting near Naco, southeast of Tuscon in Arizona, early yesterday morning.
The White House said President Obama had spoken to Ivie's family to express his sadness for their loss.
"The President told the family they are in his thoughts and prayers and made clear that his administration was doing everything it could to locate those responsible for this tragic event," read the statement.
The Washington Post said at a press conference late Tuesday, authorities told reporters a search of a rugged area near the U.S.-Mexico line was ongoing, and they were using up to four helicopters overhead in the southern foothills of the Mule Mountains, a known smuggling area.
“It’s been a long day for us but it’s been longer for no one more than a wife whose husband is not coming home. It’s been longer for two children whose father is not coming home, and that is what is going to strengthen our resolve” to find those responsible and enforce the law, said Jeffrey Self, commander of Customs and Border Protection’s Arizona joint field command.
The agents were part of a three man patrol in the area and were responding to a motion detection sensor when they encountered gunfire, according to Homeland Security officials. Authorities did not know if the agents returned fire.
Homeland Security officials said the agents were patrolling on horseback near the Mexican border when they were shot at by gunmen, the Associated Press reported.
"Border Patrol agents on patrol in Naco, Ariz., were involved in a shooting Tuesday at 1:50 a.m." US Customs and Border Protection said in a statement.
"One agent died from his injuries and another, who sustained non- life threatening wounds, was airlifted to a hospital."
The Los Angeles Times reported the agents were investigating a motion detection sensor that had been triggered when they were attacked.
According to Reuters, the town of Naco has been a smuggling corridor for marijuana trafficking and human smuggling, despite a tall fence along the border with Mexico.
"Due to the time of day and the location, we suspect some kind of narcotics trafficking, but at this point that is speculative," Cochise County Deputy Chief Rod Rothrock told ABC News affiliate KNXV.
Authorities believe that more than one person fired at the agents.
The last border patrol agent shot dead on duty was Brian Terry in December 2010. The AP said two weapons used in that shooting were later linked to the Fast and Furious gun smuggling operation.
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