One U.S. Border Patrol agent was killed and another injured during a shooting while they were on routine patrol on horseback in Naco, Ariz.

Border Patrol Agent Nicolas Ivie, 30, was killed after he and two other agents responded to a sensor hit near mile-maker 352 on Highway 80. One other Border Patrol agent sustained non-life threatening wounds and was airlifted to a local hospital. He was reported to be in stable condition Tuesday afternoon.

A third agent was not harmed.

"First and foremost, our thoughts and prayers are with Agent Ivie's family during this terrible time," said Jeffrey D. Self, commander of the Joint Field Command - Arizona. "This is a tragic loss for Customs and Border Protection. We have an unwavering commitment to pursue and bring the perpetuators of this heinous act to justice."

The shooting occurred after an alarm was triggered on one of the many sensors along the border and the three agents went to investigate, said Cochise County Sheriff's spokeswoman, Carol Capas. It is not known whether the agents returned fire, Capas said.

The U.S. government has put thousands of sensors along the border that, when tripped, alert dispatchers that they should send agents to a particular location. The area near the shooting is scattered with houses, trailers and ranchettes. Mesquite trees and creosote bushes dot the landscape and a mountain range stands nearby to the west.

The FBI, which also is investigating the shooting, declined to say whether investigators have recovered guns or bullet casings at the scene.

Patrolling some 5 miles northeast of the border, the area is known as a major drug trafficking corridor.

Drug smuggling activity tends to increase at this time of year as temperatures begin to drop from the triple digits.

Authorities have not identified the other two agents who were assigned to the Naco station, about 100 miles southeast of Tucson.

The last U.S. Border Patrol agent fatally shot on duty was Brian Terry, who was killed in a shootout with Mexican bandits near the border in December 2010. The shooting was later linked to the Fast and Furious gun smuggling operation.

The Border Patrol station in Naco was recently named after Terry.

The Terry family released a statement to the local press on the matter saying, “Today’s [shooting] is a tragic reminder of the dangers faced by the brave men and women who patrol our borders and keep our nations safe…It’s a stark reminder of the armed criminals who roam the border seeking to do harm to those who cross their paths.”

Terry’s mom took to her own Facebook following the latest news, sending her thoughts and prayers to the families of the victims.

“Another Border Patrol Agt killed closed (sic) to where Brian was killed,” Terry’s mother Josie wrote on Facebook. “My heart and prayers go out to this family. This should not happen to our Agts (sic).”

Based on reporting by the Associated Press.