FORT WORTH, Texas — Smugglers with a Mexican drug cartel targeted last week by federal authorities used homes and business parking lots in Fort Worth and Cleburne, Texas, to stash and trade weapons bound for the border, according to federal court documents.

Five acres surrounded by barbed wire in Cleburne and a south Fort Worth restaurant parking lot were among the locations where guns were exchanged, investigators said.

Smugglers transporting weapons on Interstate 35W used two-way radios to watch for law enforcement tails.

Those are among the details included in a criminal complaint filed in U.S. District Court by the Bureau of Alcohol, Tobacco, Firearms and Explosives. The weapons investigation was part of a nationwide crackdown on the violent cartel La Familia, which resulted in the arrest of 300 people last week.

Arrests occurred in 38 cities and 19 states, but officials called Dallas-Fort Worth "a critical distribution point" for the cartel.

Authorities announced last week that they had arrested nine people in Tarrant County, Texas, and two in Grand Prairie, Texas. A criminal complaint filed Oct. 19 in federal court in Fort Worth included five more people who are in custody.

The guns were purchased at Metroplex gun shops with money raised from the sale of methamphetamine smuggled from Mexico to Dallas, court documents state. One person shipped 30 to 50 weapons a week across the border.

"Gun smuggling is not just a border problem," said Tom Crowley, a spokesman for the Dallas-Fort Worth ATF office. "They have comfort zones elsewhere where they operate that extend far from the border."

A Fort Worth gun store owner brought the suspects to authorities' attention. In September 2008, the store owner notified a local ATF task force officer about two men and a woman who had purchased 20 AK-47 rifles at his store. A few days later, the woman returned to the store and bought six more rifles.

The gun store owner found the purchases "extremely suspicious," court papers state.

During an investigation, agents developed a confidential informant who told them about one man who recruited family members and their friends to buy weapons for him. Those who bought them were paid $50 extra for each gun purchased.

Once the man obtained the weapons, the informant said, it worked like this:

The man loaded them into his trunk and drove to a restaurant. While he went inside and ate, accomplices would drive the car away to another location to unload the guns. Then they returned the car to the parking lot.

Other rendezvous points for smugglers observed during surveillance were the parking lots of a Home Depot and a gas station.