Four Tarrant County men bought more than $100,000 in assault rifles over the past six months, including one that was used in a shootout in Mexico in which eight people were killed, according to a federal criminal complaint.
It is the third case in the past month in which guns purchased in North Texas have been linked to the drug war in Mexico.
The men, Reynaldo Bazan, Saul Bazan, Carlos Bazan and Obed Martinez, were arrested on Thursday by agents with the Bureau of Alcohol, Tobacco Firearms and Explosives.
It was not immediately clear if the Bazans are related.
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The men face charges of conspiracy to deal in firearms without a license.
The complaint alleges they have bought 129 assault rifles since October, usually two at a time.
One of the weapons, purchased by Reynaldo Bazan, was used in an "altercation" with the Mexican Navy in which eight people were killed, the ATF said.
The complaint did not specify where it occurred, but the details match a shootout on March 1 in the city of Valle Hermoso, near Matamoros, which is across the border from Brownsville.
According to news accounts, it was a five-hour battle. Mexican marines killed eight suspected cartel gunmen. One marine was injured. The military unit came under fire after responding to a report of a suspicious convoy of SUVs and fought back, killing the gunmen.
In the SUVs, the marines seized 12 high-powered weapons, grenades, a grenade launcher and assorted ammunition.
The arrests in North Texas follow two similar high-profile busts in recent weeks.
Just two weeks ago, three illegal immigrants were arrested after managers at a Fort Worth gun store notified authorities about suspicious purchases. The guns were destined for the violent drug cartel known as the "Zetas," the ATF said.
On Feb. 28, three Lancaster men were arrested when a gun they allegedly purchased at a Fort Worth gun show was linked to the Feb. 15 shootings of two U.S. agents in Mexico.
One of the agents, Jaime Zapata, was killed. That incident also was linked to the Zetas.