Federal authorities arrested two active members of the U.S. Army National Guard who are accused of trying to sell deadly weapons, including guns, military ammunition and body armor, to purported Mexican drug cartel members.

Jaime Casillas and Andrew Reyes, who worked in the Army National Guard Armory in La Mesa, were arrested in San Diego on Wednesday, according to law enforcement officials briefed on the federal probe. They were charged with "illegally selling firearms -- including military-issued assault rifles, ammunition and protective body armor -- to an undercover agent posing as a member of a Mexican drug cartel," the U.S. Justice Department said in a press release.

The men were allegedly caught after an eight-month undercover sting operation run by the Bureau of Alcohol, Tobacco, Firearms and Explosives, according to a federal complaint.

Casillas was arrested during a traffic stop in El Cajon, while Reyes was arrested at his home in La Mesa.

The DOJ also stated that the men allegedly "sold thousands of rounds of ammunition plus four AR15 rifles, an AK-47 assault rifle, a .40-caliber pistol and a 7.62-caliber SKS rifle to an undercover agent. The complaint alleges that some of the items were military-issued, while some were purchased by the defendants in Texas and resold to the undercover agent."

The statement went on to reveal that the informant "made clear to the defendants on multiple occasions that the purchased guns were destined for Mexico." The defendants were also aware that some of the guns acquired in Texas were either used in a crime or were stolen.

The men were scheduled to be appear in federal court for an arraignment Thursday afternoon before U.S. Magistrate Judge Mitchell Dembin to face possible charges of unlicensed firearms dealing and unlawfully transporting firearms bought out of state.