Sheriff’s officials knew about a massive house party in Palmdale. Why didn’t they stop it?

Los Angeles County Sheriff Alex Villanueva on Tuesday touted his agency’s bust of a “massive underground party” Saturday at a vacant Palmdale home, at which a teenage girl allegedly was rescued from sex trafficking, more than 150 revelers were arrested, and several guns were recovered.

However, according to law enforcement sources and an internal department record reviewed by The Times, commanders knew about plans for the party hours in advance and chose not to stop it from happening, despite the risk of coronavirus spread.

During a press conference, Villanueva defended the decision to let the party take place, saying doing so allowed the department to save the girl and to disrupt future illicit parties by arresting the people who had organized the event.

Lt. John Satterfield, a spokesman for the department, said sheriff’s officials were unaware that the girl would be at the party and discovered her by chance after deputies arrived. Villanueva, who described the organizers as “an elusive group,” did not elaborate on how their arrests will prevent future parties from occurring.

Most people were arrested on suspicion of trespassing and failing to follow a quarantine health order during a pandemic, Satterfield said. Five people accused of organizing the party were arrested on suspicion of burglary, while one 17-year-old faced a weapons charge, he said.

The operation generated criticism within the agency. One law enforcement source called it “absolutely irresponsible,” saying officials should have contacted the property owner ahead of time and, if that was unsuccessful, blocked access to the event by shutting down the street.

“Allowing it to begin, fill up with people and then roll in and make arrests is simply grandstanding and unnecessarily exposing those attendees and your own deputies,” the source said.

Satterfield pushed back against the criticism, saying that attempts to block access to the party would have led to organizers moving it to a new location.

“They would still be free to continue organizing these events. Now they have been identified and are shut down for good. Thousands of potential future exposures have been halted,” he said.

Internal activity logs obtained by The Times show the agency was preparing for the operation as early as 2:30 p.m. on Saturday, calling in units from seven stations to help out. After midnight, 80 to 100 people were being detained and would receive citations before being released, according to a log entry.

A TV crew showed up to the party, capturing footage of the operation that shows the detention of dozens of people held side by side on the street. Deputies took temperatures while handing out masks and blankets.

Since March, Villanueva has emphasized his agency’s efforts to gain voluntary compliance to health orders imposed by county officials to slow the spread of the coronavirus. He has criticized them for leaving him out of decisions about curfews and other restrictions, once saying: “If we’re the one enforcing it, and we’re not involved in the making of the plans or anything, it’s no. It’s not gonna work. Those plans are dead on arrival, unfortunately.”

After L.A. County supervisors imposed another ban on outdoor dining at restaurants, Villanueva last week spoke out against the move, saying what’s fueling the spread of the coronavirus is “not restaurants, it is private social gatherings.” A day before the party, Villanueva pledged to crack down on “super-spreader events,” where large numbers of people could be exposed to the virus. On Tuesday, he reiterated that stance, saying the business closures put owners in a difficult position of choosing between compliance and “putting food on the table for their families.”

After waiting for the party to get going on Saturday, deputies moved in around 10 p.m. on the vacant home on the 6300 block of West Avenue M-8 in Palmdale. Sheriff’s officials arrested 116 adults and 35 minors, Villanueva said. The officers found three guns that night and three more the next morning.

Villanueva said the party planners broke into the house, brazenly moving in equipment with a U-Haul truck. Capt. Ron Shaffer of the Palmdale station said the property owners did not give permission for a party.

“This is something that is worth spending our resources to clamp down on, because these super-spreader events, if we get rid of them, we’re going to improve our ability to fight the pandemic,” Villanueva said, adding that officials are tracking other events and that every weekend there are “at least probably half a dozen of these around the county.”

Los Angeles County Supervisors Kathryn Barger and Hilda Solis introduced a motion at Tuesday’s Board of Supervisors meeting to address super-spreader events. Barger cited the Palmdale event as an example of why the county must crack down on large parties. The motion directs the county’s chief executive to look for money in the budget to help the Sheriff’s Department investigate such events.

Times staff writer Jaclyn Cosgrove contributed to this report.