Police are not sure if the theft was an inside job and are currently investigating the matter.
The Los Angeles Times reports:
Members of the SWAT unit, which specializes in hostage rescues and other high-risk situations, were scheduled to train at the facility Thursday, Downing said. A police officer arriving at the building around 9 a.m. Thursday discovered the weapons were missing, according to Downing. The officer also found electrical equipment stacked near a back door, indicating the burglars may still have been working and fled when the officer arrived.
Downing said the building, although not a guarded LAPD facility, was considered secure. To get to the weapons, the thieves cut through bolt locks on an outside door and two internal doors and forced their way through a metal roll gate, he said.