Los Angeles just experienced one of the largest bank heists in its history, and the multi-million-dollar theft may have been an inside job.

One employee who works at the GardaWorld in Sylmar where the heist of some $30 million took place Easter Sunday told ABC7 he believes that the robbery may be linked to someone who has worked there. He said that the sophisticated heist looks to have been orchestrated by someone with knowledge of the facility's intricate security system. No alarms were tripped during the operation

"It's just mind blowing that you would never suspect it — $30 million in the Valley, gone. How? Why? I'm still trying to process it. Was it an inside job?" he said, speaking on condition of anonymity.

He also wondered: "Was it just one person? Was it a group? You know, there's a lot of questions."

The FBI is leading the investigation into the hiest in collaboration with LAPD officials. But officials had not released any new details as of Thursday morning.

Although the bank roof didn't seem to have sustained any damage, footage from nearby aerial views revealed a repaired gap on the southeastern side of the structure, surrounded by scattered debris of uncertain origin or relevance to Sunday's theft, the Daily Mail reported.

The staggering theft only came to the attention of GardaWorld officials when they accessed the vault on Monday. Law enforcement sources told news outlets that very few people would have known about the massive amounts of cash being stored in the safe where it was stolen.

The break-in is among the largest cash burglaries in Los Angeles history.