An attempt to steal brass and copper worth up to £5,000 in Cambridgeshire has been stopped by police.
Staff at a laboratory in Cambridge saw two men in balaclavas loading a 4x4 with metal from the premises on Wednesday night.
They followed the car onto the M11 and the police helicopter was deployed. The men got out of the car at Hardwick.
A man, 31, from Cambridgeshire and a 32-year-old man from Bedfordshire, were arrested on suspicion of burglary.
They are due to be questioned, police said.