An attempt to steal diesel in Mildenhall was thwarted after a security device went off.
The device, which had been fitted inside a diesel container at a depot in Holborn Avenue, was activated when it recognised the volume of fuel was dropping significantly.
The device sent a message to an employee, who called the police at about 10.30pm on Saturday.
Officers found a Ford Transit box van near the diesel tank, which contained five 1,000-litre bowsers and a pump, with fuel still pumping.
A second Ford Transit box van was found nearby with four 1,000-litre bowsers inside.
It is believed offenders may have fled towards Junction Road.
Anyone with information should call police on 101.