Los Angeles police late Friday were on citywide tactical alert after a wave of smash-and-grab “flash mob” robberies at high-end stores.

And in Lakewood, Los Angeles County Sheriff’s Department detectives were investigating a possible smash-and-grab robbery at a Home Depot after people stormed into the store Friday night and fled with sledgehammers and bolt cutters, according to authorities and a store employee.

Friday’s tactical alert follows a series of incidents in which groups have swooped in on stores across Los Angeles — including a Nordstrom at the Grove shopping center and several stores at the Beverly Center in the Beverly Grove neighborhood — and have fled with thousands of dollars in merchandise.

Three people have been arrested in connection with the incident at Nordstrom on Tuesday, where as many as 20 people stole $5,000 worth of merchandise after smashing a display window, police said.

In Canoga Park, several people entered a Nordstrom store Wednesday night at the Westfield Topanga & the Village shopping center, where they attacked a security guard with bear spray and took off with merchandise.

At the Home Depot in Lakewood on Friday, more than half a dozen people entered the store shortly before 8 p.m. and stole merchandise, Deputy Miguel Meza said.

“Witnesses saw multiple vehicles taking off,” Meza said.

A store employee told The Times in a phone interview that men took sledgehammers and crowbars and some wore sweatshirts with hoodies.

Detectives were at the scene late Friday interviewing witnesses.