Two U.S. Border Patrol Agents were shot today near Naco, Ariz., one agent was killed and another badly wounded.
The gunshots were possibly fired by drug traffickers, federal and county officials said.
The slain agent was Nicholas Ivie. He was 30, married and left behind two children.
His wounded partner was not immediately identified. A third agent was unharmed.
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.
The agent who was wounded was transported by helicopter to a hospital.
"Border Patrol agents on patrol in Naco, Ariz., were involved in a shooting Tuesday at 1:50 a.m.," U.S. 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."
Cochise County Deputy Chief Rod Rothrock told ABC News affiliate KNXV, "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 has been a smuggling corridor for many, many years and that seems to be unabated in modern times," he said.
Rothrock warned, "The danger zone can extend pretty far north of the border."
He said a manhunt was launched in the area, but came up empty.
President Obama called Ivie's family Tuesday to express his sadness for their loss, according to a White House statement.
"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.
Homeland Security Secretary Janet Napolitano issued a statement saying, "I am deeply saddened by the death of Border Patrol Agent Nicholas J. Ivie and the attack on another Border Patrol Agent early this morning. Both agents were on patrol near Bisbee, Ariz., when they came under fire from an unknown assailant."
She vowed to bring the assailants to justice and ordered flags flown at half staff.
Sources familiar with the sensors in the area said they are set to be triggered by a certain weight so that agents don't end up chasing rabbits or coyotes. The sensors are primarily intended to catch smugglers and some have cameras deployed with them. It is not yet know if a camera was operating in the vicinity of the sensor.
The last Border Patrol agent shot and killed along the border was Brian Terry, who was killed by bandits in a rugged part of the U.S.-Mexico border. The guns that killed Terry were linked to a disastrous gun trafficking operation run by the Alcohol, Tobacco and Firearms bureau in Arizona called Operation Fast and Furious.
The agents killed and wounded today were assigned to a Border Patrol station that was recently named after Brian Terry.
Rothrock was asked whether any of the Fast and Furious weapons could have been used in today's shooting. "I can't say that's impossible, but at this point it would be purely speculative... As we speak it is not known."