Police have arrested five men in what they are calling a sophisticated bank break-in in Burlington, Ont.

Halton Regional Police say officers were dispatched to a TD Canada Trust branch on Fairview Street at Walkers Line Monday after an alarm was activated just before 1 a.m.

Police arrived to find the bank's outside doors secure but discovered that the vault had been broken into despite an elaborate range of security measures. Police, working with their K-9 unit, established a perimeter and found the suspects hiding in the trees nearby.

Alarm bypassed, police believe

Police say the suspects gained entry to the vault through the floor of an unoccupied office building located above the bank. Police believe the suspects worked for two days to cut through the reinforced concrete floor into the vault's ceiling.

At the scene, police found an acetylene oxygen tank, concrete cutting saws, rapelling equipment, ladders and lighting gear.

Police also seized $300,000 in cash, jewelry and other items taken from safety desposit boxes.

Police believe the suspects used electronic equipment to bypass the bank's alarm system while they worked.

"In my 29 years in policing, I've never seen something of this level of sophistication," said Halton Deputy Chief Andrew Fletcher. Five men are all facing charges of breaking and entering and possession of break-in instruments.

Investigators are working to figure out if the accused may be responsible for other incidents.

With files from The Canadian Press