SEATTLE - Federal agents raided three medical marijuana dispensaries Tuesday in Seattle, where local law enforcement has taken a hands-off approach to the shops, and coordinated raids on at least 10 others around Puget Sound in the biggest crackdown since voters approved medical marijuana 14 years ago.

The Drug Enforcement Administration joined local sheriff's offices in executing search warrants at five dispensaries in Pierce County and five in Thurston County. By Tuesday evening, three search warrant affidavits had been unsealed in U.S. District Court in Seattle, suggesting that the shops were fronts for illicit drug dealing and revealing that agents were looking for evidence of drug conspiracies, money laundering and guns.

"Any state law that purports to make the distribution of marijuana legal, for any purpose, does not provide a defense to federal law," wrote DEA Special Agent Daniel Olson. "However, our investigation is not currently targeting medical marijuana providers that comply with the letter and spirit of existing state law."

Seattle U.S. Attorney Jenny Durkan echoed that in a statement Tuesday evening.

"We will not prosecute truly ill people or their doctors who determine that marijuana is an appropriate medical treatment. However, state laws of compassion were never intended to protect brash criminal conduct that masquerades as medical treatment," she wrote.

Jason Semer, who runs a marijuana industry website called www.THClist.com, said many of the busted dispensaries were clients of his. He blamed the confusing state of law.