The arrests Tuesday are the latest effort in a crackdown targeting an international network authorities said led to as many as 60,000 weapons being seized in Mexico and traced to sources in the United States, the Los Angeles Times reported.
"The massive size of this operation sadly exemplifies the magnitude of the problem -- Mexican drug lords go shopping for war weapons in Arizona," Dennis Burke, U.S. attorney in Arizona, said in a statement.
The case involves using "straw purchasers," legal residents in a state who buy weapons from licensed gun dealers, certify that they are for personal use, and then sell them to Mexican drug cartels, federal officials said.
None of those charged are licensed gun dealers, but the indictments identify several Arizona dealers that legally fulfilled orders for large numbers of weapons for individual buyers, often in one day, the Times said.
The federal Bureau of Alcohol, Tobacco, Firearms and Explosives said the case highlights the need to include long-barreled weapons in the requirement that gun sellers report multiple weapon sales to a lone buyer, the Times said. The National Rifle Association and many gun owners oppose the proposal, saying it is an overreach of federal authority.