Bundles containing thousands of pounds in cash keep turning up on the streets of Blackhall Colliery in northern England, according to police. Residents of the village have been coming across bundles of £20 notes—usually worth £2,000—in the former mining village in County Durham.

The latest discovery was on Monday, meaning four of these cash bundles have been handed in this year and 13 since 2014.

The bundles are usually left in plain sight and have been scattered across the small coastal village. The owner has two weeks to collect the cash, which is then returned to the finder if not claimed, according to Peterlee Police.

A Durham Police spokesperson said the money has been returned to the lucky finders in all cases except yesterday.

Policeman John Forster said in a statement: “The circumstances remain a mystery so we would welcome any information that will help us get to the bottom of these random incidents.”

He told The Northern Echo: “It isn’t an affluent part of the world, so for them to find cash of that amount and instantly think about taking it to the police stations shows the community spirit there is.”