EDMONTON -- Construction crews recently unearthed a century-old mystery in a town west of Edmonton.

Crews initially thought they had found a washout under the Town of Stony Plain, but as it turns out, they actually discovered a tunnel that led…to a bank.

"We do know that this was a bank and we do know that it was breached so we're trying to look for some maybe old police reports way back in 1918-1920 area of time to see if there was a reporting of a bank robbery," said Mayor William Choy.

The man who discovered the tunnel, Mike Moeller, said the tunnel wasn't very sophisticated.

"All hand tools…you can see where there was digging marks on the side, so they must have used hand tools, shovels, that kind of stuff."

And that's not all Moeller found. There were also oil tanks and a water vault used to collect rain water from buildings close by and for fire trucks that would come to collect water.

Choy said the water vault was built in 1924.

The mayor called the discoveries and possibility of a robbery in the town of Stony Plain "fascinating."

With files from CTV News Edmonton's Amanda Anderson