The seizure of more than 700 guns and the indictments of 34 people announced on Tuesday are further confirmation that Arizona has become an iron highway for weapons into Mexico, according to federal authorities.

Many legal purchases by straw buyers at Arizona gun stores are being financed and orchestrated by Mexico's Sinaloa cartel, federal officials said.

The cases announced Tuesday involved the purchases of many AK-47s, .50-caliber rifles and other semiautomatic weapons in single-day transactions at gun stores by straw buyers paid by the cartel, U.S. Attorney for Arizona Dennis Burke said.

"This is a huge problem in this state. It is a strange phenomenon," Burke said at a news conference at the Phoenix office of the Bureau of Alcohol, Tobacco and Firearms and Explosives. "Drug cartels go shopping for their war weapons here in Arizona."

At least 17 people were arrested Tuesday in five cases involving a joint crackdown by the ATF, Immigrations and Customs Enforcement, the Internal Revenue Service and the Phoenix Police Department.

Burke said the five cases have gutted an entire firearms organization in Arizona from top to bottom, from straw buyers to organizers to financers.

Charges include making false statements on federal firearms-purchase forms, conspiracy and possession of a firearm in furtherance of a drug-trafficking offense, according to the indictment.

"Straw buyers have as much blood on their hands . . . as the ones who pull the trigger," said Bill Newell, special agent in charge of the Phoenix ATF.

All of those indicted are U.S. citizens or legal residents.

The indictments reveal the relative ease with which citizens who have not been convicted of a felony can amass an arsenal of weapons.

For instance, according to the indictments, defendant Joshua Moore bought six AK-47 and similar rifles from a gun store in Prescott in 2009. Three days later, he bought two AK-47s from a gun store in Glendale. Seven days later, he bought 10 from the same store. Two days later, he bought five more there. Less than a month later, he bought 20 from the same store. Three months later, he bought 10 more from the Glendale gun store.

The purchases themselves are legal; nothing in the law prohibits citizens who pass background checks from buying long guns, such as AK-47s, or handguns. But authorities say Moore lied on federal firearms applications by declaring that he was buying the guns for himself when he was really supplying them to cartel front men.

Newell said the guns were traced back to buyers only after they were seized by customs inspectors at border checkpoints or after being used in crimes in Arizona and Mexico, including immigrant smuggling, kidnapping and drug dealing. A chart illustrating seizures in the largest of the five cases showed that 372 guns were recovered in the United States and 195 in Mexico.

In some cases, the guns were recovered at U.S. Customs and Border Protection southbound checkpoints just days after their purchases; 12 AK-47s were hidden inside a stove, nine in a vehicle bumper.

In Arizona, there is no waiting period for buying handguns or long guns following a standard background check. Also, sales of single guns are not reported to federal or local authorities at the time of purchase. Local and federal authorities must be notified when two or more handguns are purchased within a week. But there is no reporting requirement for purchase of multiple long guns.