The thieves struck at a Kevin Jewelers about 11 a.m. Tuesday morning at the shopping mall near the intersection of Imperial Highway and the 57 Freeway, a spokesperson for the Brea Police Department told ABC7.
Officers arrived at the scene and discovered that the suspects -- identified only as between five and eight males wearing masks -- had already fled in two separate vehicles," police Lt. Chris Haddad said. Additional descriptions were not available.
Haddad said investigators were reviewing surveillance video, adding that there was "pretty substantial evidence in this case."
The robbers used sledgehammers to break glass at the jewelry counter, police said. No injuries were reported.
The amount of jewelry stolen was not specified, but Haddad described it as a "particularly large dollar amount."
"It's one of the lowest-crime malls in Southern California," the lieutenant said of the Brea Mall. "That said, we're not immune to crime."