Thieves have made off with more than $10 million in merchandise from a small, family-owned jeweler in Los Angeles in a cinema-style heist.

Extraordinary photos show the burglars managed to tunnel through a concrete wall in order to gain access to Love Jewels on Broadway in downtown LA on Sunday night.

The devastated owners only learned of the break-in when they arrived to work on Monday morning because the thieves had taken extraordinary steps to avoid detection.

In addition to the tunnels, no alarms went off at the time of the break-in, and the in-store security cameras had been disabled from within.

Officer David Cuellar with the LA Police Department said in a statement on Tuesday that the burglars 'tunneled through multiple levels of concrete into the target location.'

Investigators were reviewing security camera footage that shows the suspects entering the store from a large hole they drilled from the property next door, he said.

An unknown number of suspects fled through the same hole after pillaging for six hours and drove off in a late model Chevy truck.

While initial estimates suggest about $10 million worth of merchandise was stolen, the owners said it is likely closer to $20 million.

Watches, pendants, cash, gold chains and solid gold bars were among the products taken by the thieves. 

The owners said they do not have insurance because it was too expensive, and have offered a $100,000 reward for information relating to the incident.

The family believe the thieves spent weeks painstakingly digging the hole, which connected the shop to an abandoned theater next door.

'They probably went in there every night, slowly dug it until there was enough room for them to get in,' the store owner's son told NBC Los Angeles. 

At least one of the two safes was accessed easily, leading the owner's son to suspect one of the thieves was a locksmith or had experience in a similar field.

'They cleared out everything,' he added. 'They didn't leave a dollar for us.

'In the gold business, you reinvest everything, so all our money was what was in the safe.'

On Tuesday, workers were at the store patching up holes in the walls and attempting to repair the damage.

Display cabinets had been overturned and boxes were strewn over the floor.

Two large safes were broken into, containing all the merchandise they had in the store.

Customers and friends stopped by to offer sympathy, with some even asking to purchase items.

Love Jewels' website advertises items like a 14 karat yellow gold rope chain for $1,200, heart-shaped gold earrings for $200 and a gold cross pendant for $550. 

Videos on the store's social media shows glass cases filled with rings, watches and necklaces.

Detectives examined the scene for fingerprints and DNA, police said.

Thieves pull off Hollywood-styled heist to steal $10M in jewelry from family-owned LA store