Los Angeles police and the Federal Bureau of Investigation, FBI, are investigating a daring robbery of nearly $30 million in cash after burglars broke through the roof of a money storage facility and cracked a safe.

David Cuellar of the Los Angeles Police Department said the robbery — one of the largest cash thefts in the city’s history — took place on Easter Sunday in the northern suburb of Sylmar.

According to the Los Angeles Times, citing a source familiar with the investigation, the burglars busted through a roof to access the building’s vault, somehow evading a sophisticated alarm system.

The elaborate and sophisticated theft appeared to be the work of an experienced crew, and was only discovered on Monday when staff opened the vault, the newspaper said.

“It’s just mind-blowing that you would never suspect it,” an anonymous employee of the facility told ABC News.

“$30 million in the Valley, gone. How? Why? I’m still trying to process it. Was it an inside job? Was it just one person? Was it a group? You know, there’s a lot of questions.”

The crime, likened to the Hollywood heist movie “Ocean’s Eleven,” followed a string of real-life, sophisticated break-ins in the region over the years.

Two years ago, it was reported that Thieves made off with up to $100 million in jewels from a truck parked at a highway rest stop en route to a gem and jewelry show in Los Angeles.

In a similar incident last July, a man cut a hole in the ceiling of a high-end wine store near Venice Beach, before helping himself to $600,000 worth of fine Burgundy and Bordeaux vintages.

The largest previously known cash heist in the city’s history, according to the LA Times, came in 1997, when $18.9 million was stolen from an armored depot. The thieves were subsequently arrested.