A U.S. Border Patrol agent was killed and another wounded in a shooting early Tuesday in Arizona near the U.S.-Mexico line, according to the Border Patrol.  The agents were shot while patrolling on horseback in Naco, Ariz., at about 1:50 a.m. MST Tuesday, the Border Patrol said in a statement. The agents who were shot were on patrol with a third agent, who was not harmed, according to George McCubbin, president of the National Border Patrol Council, a union representing about 17,000 border patrol agents. “It’s a tragic reminder of the dangers the brave men and women who guard our borders face every day,” said House Oversight and Government Reform Committee Chairman Darrell Issa, who has been investigating gun-running connected to a failed Justice Department operation called Fast and Furious.

“Just last month, I attended a ceremony with agents based at the Bisbee station naming it in honor of their fallen colleague, Brian Terry,” Issa said in a statement. “My prayers are with the family of the agent who lost his life today and his wounded colleague.“Authorities must investigate the full circumstances of this shooting. I urge everyone to think of the families of these agents and avoid drawing conclusions before relevant facts are known.”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.Authorities have not identified any suspects, Capas said. It is not known whether the agents returned fire, she said.The wounded agent was airlifted to a hospital after being shot in the ankle and buttocks, the Border Patrol said. He is in surgery and expected to recover, McCubbin said.

Authorities have not identified the 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 FBI, which also is investigating the shooting, did not immediately return calls Tuesday.

Arizona straddles a major route for Mexican smuggling networks hauling drugs and illegal immigrants north to the United States, and running guns and cash profits back south to Mexico.

The area near where the agents were shot made headlines in February when border agents broke up a drug trafficking network which led to a bust of 15 tons of cocaine and marijuana. In that raid, 12 suspects were arrested.

At the time, police had seized more than 30,000 pounds of marijuana and cocaine linked to the trafficking organization, which had been active for more than 15 years, the Daily Mail reported Tuesday.

The organization used backpackers and vehicles to run the drugs across the rugged, high-desert borderlands around Naco, in smuggling forays several times a week.

Once in the United States, the drugs were stored at various stash houses in Naco, nearby Bisbee and Tucson, around 100 miles to the northwest.

A report by Univision on Monday uncovered that firearms from the “Fast and Furious” operation were linked to at least two massacres in Mexico and the 57 previously unidentified firearms linked to the botched operation were recovered in sites associated with murders and kidnappings.

In one of the massacres in 2010, a commando of “at least 20 hit men,” according to Univision, opened fire on a party of 60 teenagers in Ciudad Juarez, killing 14 and wounding 12. The assailants were hired by a Mexican cartel. Three of the high caliber weapons fired that night were linked to the Fast and Furious operation, Univision reported.

Univision obtained a list of Fast and Furious weapons and a list containing almost 60,000 recovered firearms compiled by Mexico’s defense secretary and then cross-referenced the data, and got 96 full matches. The 96 firearms linked to Fast and Furious all turned up at crime scenes in Mexico from 2009 to 2010, Univision reported.

Approximately 300 Mexicans have been killed or wounded by Fast and Furious guns, estimates former Mexican attorney general Victor Humberto Benitez Trevino.

Between November 2009 and January 2011, the Obama administration arranged for licensed firearms dealers in Phoenix, Arizona to sell guns to straw buyers, who transferred them to known violent criminals in Mexico. These arms were supposed to lead federal agents in Phoenix to the Mexican criminals who acquired them. Instead, agents lost track of the guns, and in 2010, two were found near the body of slain border patrol agent Brian Terry.

Congressional Republicans have pressed for investigations and a report by Justice Department Inspector General Michael Horowitz skewered the Fast and Furious operation as “seriously flawed” and said agents for the Bureau of Alcohol, Tobacco, Firearms and Explosives ignored consider public safety as they let about 2,000 firearms fall into the hands of Mexican drug cartels as part of the operation.

The House voted to hold Attorney General Eric Holder in contempt earlier this year after he refused to turn over certain documents, citing executive privilege.

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