Three high-ranking Mexican police officers were detained for violation of a law barring non-citizens from purchasing firearms.
The three include the director of the Baja California state police and a commander of the federal police in Baja California, said Tom Mangan, a spokesman with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives.
The three had crossed the border in California in an official police vehicle and driven to Phoenix. They were arrested by Phoenix police and Immigration and Customs Enforcement agents after buying three handguns and about 450 rounds of ammunition Saturday at the gun show, Mangan said.
He said it appeared the officers were buying the handguns for their personal use.
Police booked Carlos Alberto Flores, 36, the Baja California state police director, on state weapons misconduct and conspiracy charges, according to a Phoenix police report. State police Commander Guillermo Valle Medina, 33, was booked on the same felony charges, as was Jose Santos Cortes Gonzalez, 41, a commander in the federal police, the Mexican equivalent of the FBI.
Flores and Cortes posted $2,000 (1,440 EUR) bond each and were released from jail, and Valle was released on his own recognizance, Mangan said.
A woman who answered the telephone in Flores' office in La Paz said he was still in charge but not in the office or available for comment. A spokeswoman for the state Office of Public Safety that oversees the police, Alejandra Borquez, said she was unaware of the incident.
The three were allegedly seen by local and federal authorities buying the weapons and ammunition at the show and were arrested after leaving the venue, according to a police report.
Mangan said Mexican officials have been pressuring U.S. officials to cut off the supply of weapons going south.
"It is ironic we are receiving a great deal of criticism regarding our efforts to stem the tide of illegal weapons, and then we have three law enforcement officers trying to buy weapons here," Mangan said.
Mangan said gun shows in Arizona can have a mix of federally licensed dealers and private citizens selling weapons. Licensed dealers must run check identification documents and run background checks, but private sellers operate without those rules.
The guns were bought from a private seller, he said.