CERRITOS (CBSLA.com) — The Los Angeles County Sheriff’s and Fire departments Tuesday conducted an active shooter training exercise at a mall in Cerritos.

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KNX 1070’s Jon Baird reports the 6 a.m. drill involved more than 100 personnel from the Cerritos, Lakewood, Norwalk and Pico Rivera Sheriff’s Stations, the Cerritos Community Emergency Response Team, mall security and store employees at Los Cerritos Center.

L.A. County Sheriff’s deputies practiced three separate incidents – all involving a person with a gun going into a shopping mall – along with participation from mall security personnel and even some store employees.

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“Law enforcement nationwide trains like this all the time,” said Cerritos Sheriff’s Capt. Keith Swensson. “It’s heart-wrenching when you see something like that that happens at LAX, but you can’t prepare for everything.”

The drill comes in the wake of Friday’s LAX shooting. Los Angeles Airport Police had recently undergone similar training, which has been credited for the quick resolution of the incident.

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The mall opened for business as usual following the conclusion of the drill at 10 a.m.