Thieves are targeting vans in two neighbouring Rotherham suburbs.
Tools have been stolen from a number of vans in Aston and Swallownest, with police officers now urging people to remove all valuables from their vehicles at night.
Officers have also been carrying out checks on vehicles to ensure they are locked at night.
A Rotherham South Local Policing Team spokesman said: "We are aware that recently there has been a rise in vehicle related crime in the Aston and Swallownest areas.
"Offenders are targeting work vans of all different makes and models by peeling back doors to gain entry. Work tools are being stolen.
"Whilst we understand it is difficult to remove everything from your van every night, we recommend if you live in this area that you do not leave anything expensive in the vehicle or anything on show that is attractive to thieves.
"We have been doing some work in your area to target vehicle owners and offer crime prevention advice. We have also been checking motor vehicles on Gray Avenue and Arcubus Avenue to ensure that cars are not left insecure, which makes vehicles an easier target.
"Out of the 37 vehicles that we checked, we found two to be insecure. If you live on these streets, you will have received a leaflet about motor vehicle crime and how to prevent it.
Residents are warned to be extra vigilant at this time and report any suspicious activity."
Call South Yorkshire Police on 101.