SAN DIEGO (AP) — Federal agents raided 13 San Diego-area marijuana dispensaries Monday, seizing large quantities of the drug, computers and records in one of the largest crackdowns of its kind in California.

Authorities said the shops were selling marijuana to people who weren't using it for medicinal purposes. The home of one of the dispensaries' owners was raided along with the shops.

"These were nothing more than a front for distributing marijuana," said Drug Enforcement Administration agent John Fernandes.

One man, armed with a firearm, was arrested as he drove up to a dispensary with two pounds of marijuana he was trying to sell — apparently unaware of the raid taking place.

Steph Sherer of Americans for Safe Access, a medical marijuana advocacy group, called the raids outrageous and a cowardly act of an administration that was out of touch with voters.

In 1996, California voters passed a ballot initiative that decriminalized the use of medical marijuana under state law. However, under federal law, it is illegal to use pot even for medical purposes.

Authorities began investigating San Diego's dispensaries six months ago, prompted partly by complaints from neighbors. Instead of providing marijuana to seriously ill patients as voters had intended, dispensaries that were raided Monday sold marijuana to young adults, Fernandes said.

The combination of drugs and cash also has attracted armed robbers, he said.