Robbers held three employees of a California security company at gunpoint and left them tied up in a vault before fleeing with more than $1 million in cash, police said.
Los Angeles County Sheriff's Sgt. Steven Ruiz said that the robbery was reported at 8:43 p.m. on Thursday.
The robbers broke into the building through the roof and surprised the workers, he said.
"Upwards of $1 million was taken," Ruiz told msnbc.com. "We have investigators currently working the case."
Ruiz added that no one was injured.
News reports identified the business as Commonwealth International, a security service that transports money from automated teller machines.
The firm's answering service took a message but said no one from the firm was available early Friday.
Ruiz said that at least one suspect was armed. The victims were found tied up in the vault when officers arrived, he added.
The two guards were being investigated and had been suspended with pay, citing sources close to the investigation.