Police in the U.K. are investigating after thieves raided a safety deposit box vault in London's jewelry district over the Easter weekend.

According to local media, the thieves may have made off with stolen goods worth as much as an estimated $350 million, CTV's Daniele Hamamdjian reported from London.

But it's the way the thieves may have accessed the Hatton Garden safety deposit boxes that's drawing much attention.

Police said heavy cutting equipment was used to break into a vault at Hatton Garden Safe Deposit Ltd.

With no obvious signs of forced entry to building, Hamamdjian says there is speculation the thieves somehow managed to get through the roof of the building, then used rappelling gear to get down an elevator shaft. It is believed that they used heavy equipment to bore through a door, which gave the thieves access to a vault.

It is believed that once inside the vault, the thieves drilled through up to 70 safety deposit boxes, Hamamdjian said.

"It's audacious," she said. "It is the stuff of crime movies, except this is reality."

Hamamdjian said it was only when staff at the Hatton Garden Safe Deposit Ltd. returned to work after the Easter long weekend on Tuesday, that they realized what had happened and alerted police.

"For all we know the burglars or the professional thieves could've had four days to do this," she said.