Police are urging van drivers to be extra careful after thieves targeted vehicles parked in the Swinton and Wombwell areas.
Tools worth more than £1,000 were taken from vans parked in the Dearne areas, along with other thefts across Barnsley and Doncaster.
A police spokeswoman said: “People need to ensure that work vehicles — which often contain thousands of pounds worth of equipment — are secure. We’d urge workers to unload vans of anything that’s valuable and store them in a safe place, as well as making sure that the key is not left in the ignition when deliveries are made.”
She continued: “Any break-in can be costly and inconvenient not only for you, but also for your employer.”