A spate of thefts from vans in the Harborough district in the last two weeks has led police to again warn local tradespeople: "Don't leave anything valuable in your van overnight".
Sgt Kev Manship at Market Harborough police station said: "We believe thieves are coming in from outside the area, as well as local people.
"We are trying to police this, and have asked for extra resources to help us. But we need van owners to help us as well."
A couple of the more brazen thefts have happened during the day. On one occasion, a group of men in high-vis jackets stole tools from a van parked in Sainsbury's car park in Market Harborough.
But most of the thefts are at night.
Sgt Manship told the Mail: "Would you leave £5,000 in your car, waiting to be stolen? You just wouldn't. That's why you should never leave expensive bits of kit in your van.
He said tradesmen should always remove tools and other items from their vans at night. "If you can't afford to lose it, take it out."
He said items in vans should be insured, and vans should be alarmed. Owners should also consider motion-sensitive dashcams.
Van owners should also, where possible, park their vehicles overnight with the doors up against a wall or another vehicle.