DETERMINED thieves towed away two mini-excavators.
The intruders brought specialist cutting gear to get into the Yorkshire Electricity compound on Crosland Road, Oakes, between 8.10pm and 8.25pm on Sunday.
Their targets were the two £8,000 machines, each on a trailer.
The thieves hooked the trailers up to a white Ford Transit van and a white Land Rover and drove off. Det Con Steve Shaw, of Huddersfield CID, said: "The thieves went well prepared and knew what they were after.
"People may have seen them towing the excavators away and not realised a crime was being committed."
Anyone with information should phone Det Con Rob Rutherford at Huddersfield CID on 01484 436746.