Thieves in Swindon made off with a speed camera after using a power tool to cut the machine from its stand.
The Gatso camera, worth up to £40,000, was taken from the central reservation in Queens Drive, late on Thursday night or early Friday morning.
A police spokeswoman said the camera was heavy and it would have taken at least two people to drag it away.
"This doesn't serve any purpose other than increasing the risk of casualties," she said.
It could take weeks to replace the fixed camera and police have warned that in the meantime they will step up the use of mobile camera units in the area.
The spokeswoman said the Wiltshire force's speed cameras had been vandalised before, but this was the first time one had been stolen.
"What they (the culprits) don't realise is that speed cameras are not put up for the fun of it," she said.
"They are there because an area has a history of speeding casualties."