The Los Angeles Police Department and FBI are investigating the theft of tens of millions of dollars in cash from a money storage facility in what appears to be the largest heist in LA history.

A law enforcement source familiar with the investigation confirms with CBS News that the heist took place at GardaWorld in Sylmar on Easter Sunday, with as much as $30 million stolen. The source says it appears to be a sophisticated operation.

The source told CBS News that burglars broke through the building’s roof and gained access to the vault without triggering the facility’s alarm system.

Read more: cbsnews.com