Several people were detained, although no arrests were made after five dispensaries in West Hollywood and six others in Venice, Hollywood and the San Fernando Valley were searched Wednesday, said Sarah Pullen, a spokeswoman with the U.S. Drug Enforcement Administration.
Pullen declined to provide details of the investigation, saying the search warrants remained under seal.
"But obviously we are looking for marijuana and other illegal drugs, marijuana edibles and evidence of ongoing criminal activity and anything from paperwork to documents — you name it," Pullen said.
City officials in West Hollywood said they were surprised by the action, learning of the raid as it was happening.
West Hollywood spokeswoman Helen Goss said the city has a "long-standing commitment" to the use of medical marijuana for people suffering from illnesses like HIV and AIDS.
Agents in bulletproof vests, gloves and face masks left a West Hollywood storefront with boxes and trash bags filled, as about 50 protesters booed and shouted "states' rights."
At one dispensary, The Farmacy on Santa Monica Boulevard, amateur videographers and others mobbed officers filling three cars with evidence.
California voters approved Proposition 215, the Compassionate Use Act, in 1996. It made marijuana available by prescription for medicinal uses.
The DEA, which does not recognize California laws legalizing medical marijuana use, has recently increased its enforcement.
"Today's enforcement operations show that these establishments are nothing more than drug-trafficking organizations bringing criminal activities to our neighborhoods and drugs near our children and schools," said Ralph W. Partridge, head of the DEA in Los Angeles.