Fire crews from Chippenham and Malmesbury went over the border into Gloucestershire last night to assist with a major blaze in Stroud.
At the height of the incident, 15 crews were tackling the fire at the Nu-Pro factory off London Road, including the two from Wiltshire.
Nu-Pro is described as a key manufacturer in the aerospace and defence industries, and the 50m x 30m factory contained a quantity of chemicals.
Gloucestershire Fire & Rescue Service received the 999 call at around 8.30pm last night and, once the scale of the fire was known, crews from Chippenham and Malmesbury were mobilised to the scene, supported by an officer.
An appliance from Stratton was then sent to provide a relief crew and was the last Wiltshire Fire & Rescue Service crew to be released from the incident, just before 2am.