As dusk settled on busy Colorado Boulevard, a squad of minivans and SUVs pulled to the curb outside a drab stucco rental that houses one of Eagle Rock’s medical marijuana dispensaries.

Plainclothes narcotics officers fanned out. One disarmed a startled security guard, another covered the door through the sights of a rifle and a third phoned the shop to announce the raid. A second guard, three employees and a dozen grim-faced customers filed out, hands in the air.

By the end of the operation, the officers had arrested the Colorado Collective’s owner and an employee and hauled away 40 pounds of marijuana and $17,000 in cash in large evidence bags.

The raid was the fourth by a new Los Angeles Police Department team that is spearheading an aggressive push to shut down dispensaries that are illegal under a city ordinance that took effect four weeks ago.

“This is a high priority for the City Council and a high priority for the city attorney, so it’s a high priority for us,” said Capt. Kevin McCarthy, head of the Gang and Narcotics Division.

The ordinance allowed dispensaries that registered with the city in 2007, when it adopted a moratorium on new pot shops, to remain open. The rest, which opened in defiance of that ban, had to close by June 7. City officials say there were more than 400 illegal dispensaries, but they think most have since closed.

Asha Greenberg, an assistant city attorney who is overseeing the enforcement efforts, said she believes that as few as 20 to 30 illegal stores may still be defying the ordinance. “It’s also somewhat of a moving target,” she said, “because we hear of places open up and then close, we hear about places that have cut down on their hours and some places that have now turned into delivery services, so it runs the gamut of these places trying to get around the ordinance.”

In Eagle Rock, which emerged as the epicenter of the neighborhood activism against the pot-shop explosion, most of the unauthorized outlets that once ringed the area appear to have closed.

On Colorado Boulevard, the shades were drawn at ABC Caregivers and only the outline of the letters CNC remained on the glass door at CN Collective on West Broadway. The building on York Boulevard that had been Northeast Collective was being refurbished by a hypnotist who plans to open a clinic.

Several dispensaries, among scores that have sued the city to challenge the ordinance, hope to win a court order that will allow them to reopen. At the House of Kush on Colorado Boulevard, a printed sign said: “We are closed until further notice. Sorry for the inconvenience.” Organic Healing Center, also on Colorado, posted a hand-written note: “We are doing our best and fighting hard to get safe access back for you.”

At the Hummingbird Collective on York Boulevard in neighboring Highland Park, Marty Romero, one of the operators, watched as equipment was carted out and loaded into a U-Haul. The store, part art gallery, part hippie hangout, was filled with paintings, books and overstuffed furniture. A Buddha sat serenely near a glass door with the word “kindness” hand-painted on it. “We just took off ‘love,’ ‘peace’ and everything else, but it still says ‘kindness,’ ” Romero said. “The vibration was incredible.”

Under the ordinance, the city could seek court orders to close dispensaries and impose civil fines, but that is costly, ponderous and often ineffective. Instead, the city attorney’s office settled on the bluntest approach: criminal prosecutions that allow police to confiscate cash and pot and leave dispensary operators facing up to six months in jail on misdemeanor charges.

The tactic has dismayed medical marijuana advocates. “It seems ridiculous. These are peaceful people. It seems to me that there’s still reefer madness,” said Dege Coutee, who runs the Patient Advocacy Network. “It doesn’t make any sense to just steal the cash and the herb.”

To coordinate the raids, LAPD officials have assembled a team of eight narcotics officers. The team conducted three busts before the one at Colorado Collective, making a half-dozen arrests, seizing $7,265 in cash and 43 pounds of marijuana at Kush Korner II in Wilmington, Nirvana Pharmacy in Westwood and Kind for Cures in a former Kentucky Fried Chicken store in Palms.

The city is primarily targeting dispensaries fingered by residents who have been e-mailing between five and 10 complaints a day to atty.medicalmarijuana@lacity.org. “They are our best source because they are frequently in the neighborhood,” Greenberg said. “Some of these places, if the LAPD drives up in a marked car, they will close the door and pretend to be closed.”

The afternoon before the raid at Colorado Collective, two undercover officers walked into the dispensary posing as prospective clients. They filled out the required paperwork and were allowed to enter an inner room where the shelves of a long glass cabinet were lined with two dozen jars filled with pungent buds. The officers bought about $30 worth of pot and, because it was their first purchase, the “budtender” threw in a free joint.

Within a few hours, the officers had obtained a search warrant from a judge and convened with the rest of the task force. After a quick briefing, the officers strapped on bullet-protective vests and helmets and drove to the dispensary.

Inside, they moved from room to room, finding refrigerators and cupboards full of marijuana in jars, and tried to persuade Larry Lo, the dispensary’s operator, to open a large safe.

“Larry, you’ve got to think a little bit here,” said Lt. John King, who supervises the team. “We’re not here because we’re having fun. We’re here because we’ve got a warrant to search this place. I’m going to get into that safe one way or the other. I don’t want to, but I will ruin it if I have to.”

Lo was not swayed, so King called for a lock specialist, who arrived hours later and spent several more drilling into the lock to open it. When the safe finally popped open, police found it filled with cash and more marijuana. The seized pot could have a retail value of about $250,000 or more.

Evidence seized by police during such raids could be returned if those arrested do not face charges or are found not guilty.

Handcuffed and seated on a coach, Lo repeatedly insisted that his dispensary was registered with the city and allowed to operate.

“There must be a misunderstanding. I can show you the paperwork,” he told King. But King said, “We’re here because the city attorney says you’re one of the unfortunate ones whose license is null and void. You need to take it up with them.”

City records show that Lo did register in 2007 at the same Colorado Boulevard address, although he used the name Southern California Collective. And he recently notified the city that he planned to continue operating his collective under the new ordinance. Lo, who spent a night in jail after his arrest, declined to comment.

Police said the dispensary was on a list provided by the city attorney’s office. Greenberg noted that the collective was operating under a different name and said the office had received complaints about it, but declined further comment on the raid.

“That’s something we’re still looking at,” she said.

joel.rubin@latimes.com

john.hoeffel@latimes.com