LOS ANGELES >> A group of thieves smashed windows at a department store at a luxury mall in Los Angeles, triggering a police pursuit just days after high-end stores throughout the San Francisco Bay Area were targeted.

The latest incident in a national trend of smash-and-grab crimes targeted a Nordstrom store at The Grove retail and entertainment complex. It came as the country’s largest consumer electronics chain said an increase in organized theft was taking a toll on its bottom line.

Workers covered a large broken window at the Nordstrom with black plywood Tuesday morning as security guards and shoppers alike came in and out of the store. Michel Moore, chief of the Los Angeles Police Department, said the agency would beef up its visible patrols around high-end stores citywide beginning Tuesday night and into the Thanksgiving and Black Friday weekend.

Crimes like these “have a profoundly greater impact on the sense of safety and security than simply the dollar loss of the merchandise,” Moore said.

The thieves struck around 10:40 p.m. Monday, using a sledgehammer and an e-bike to break the window’s glass, Moore said. About 20 people were involved in the smash-and-grab theft, stealing about $5,000 worth of merchandise and leaving roughly $15,000 worth of damage to the store when they fled.

Officers pursued an SUV involved in the crime, and the chase ended with three people — including a juvenile — arrested. Officers found Nordstrom merchandise in the SUV, as well as items that appeared to be stolen during a CVS burglary earlier in the day.

The Grove incident followed a weekend of similar brazen thefts in the San Francisco Bay Area and Beverly Hills in which groups of people, some carrying crowbars and hammers, ransacked high-end stores and stole jewelry, sunglasses, suitcases, clothing and other merchandise before fleeing in waiting cars.

The thefts are believed to be part of sophisticated criminal networks that recruit mainly young people to steal merchandise in stores throughout the country and then sell it in online marketplaces. Experts and law enforcement officials say the thefts are ratcheting up as the holiday shopping season gets underway.

The National Retail Federation said a recent survey found stores are seeing an increase in organized thefts and perpetrators being more aggressive.

The electronics chain Best Buy on Tuesday cited organized theft as one of the reasons for a decline in gross profit margin in the third quarter.

“This is a real issue that hurts and scares real people,” Best Buy CEO Corie Barry told analysts during a conference call Tuesday.

Barry told reporters during a separate call that the company is seeing organized theft increase across the country, but particularly in San Francisco. She said the company is hiring security guards and working with its vendors on creative ways to stage products.

Yet loss prevention agents and security guards are generally trained not to engage with thieves, said mall and retail security expert David Levenberg. They are not trained or equipped to pursue or subdue suspects, and the likelihood of violence is too great; instead they are supposed to “observe and report.”

“The value of the merchandise is not worth somebody being injured or killed,” he said.

Workplace security expert Hector Alvarez said retailers need to think about how to manage their customers while a smash-and-grab theft is underway. Stores have an obligation to keep their shoppers safe during these events, he said, like they would if a fire occurred.

Customers should not intervene or confront the thieves, he said, but focus on being a good witness for law enforcement.

While these brazen crimes are still relatively rare, “it’s now become hazardous in some instances to go shopping,” said Alvarez, president of California-based Alvarez Associates LLC.

No shoppers were reported injured in the latest incidents.

The flash mobs are usually organized by local people who recruit their crews and send them to steal specific merchandise requested by criminal organizations throughout the U.S., said Ben Dugan, president of the Coalition of Law Enforcement and Retail.

Those who do the stealing get paid between $500 and $1,000 to take as much as they can and bring it back to organizers who ship it to other parts of the country.

“Crew bosses organize them. They’ll give him the crowbars, and in some cases even rent them cars, or provide them with escape routes or a list of products to actually go out and steal. It looks very chaotic, but it’s actually very well organized,” Dugan said.

“We’re not talking about someone who needs money or needs food. These are people who go out and do this is for high profit, and for the thrill,” he said.

In some cases, though, the thieves may be copycats rather than people working with organized networks, Levenberg said. He said the thieves may be thinking: “‘Did you see what happened in San Francisco? Let’s go to the Grove and do it.’”

And while smash-and-grab thefts are occurring nationwide, Levenberg said cities with progressive prosecutors — like Los Angeles and San Francisco — are especially hard-hit because the punishments for perpetrators are not as harsh as in other cities.

“The consequences are minimal, and the profits are substantial,” said Levenberg, founder of Florida-based Center Security Services.

California Gov. Gavin Newsom said Monday that his office met with retailers over the weekend who asked for more police patrols.

He said increased enforcement would start immediately “in and around areas that are highly trafficked and coming into the holiday season Black Friday in shopping malls.”

Retailers lose about $65 billion each year to organized theft, the bulk stolen by professional thieves, Dugan said.

Last week, 14 suspects went into a Louis Vuitton store in Oak Brook, a Chicago suburb, pulled large plastic bags from their coats and filled them with clothing and other items, stealing more than $120,000 in merchandise, police said.