Fire crews tackled a blaze after being alerted by residents who found their street had become smoke-logged.
Firefighters traced the smoke to a single storey building in between two mills at Peel Park Works, Undercliffe Road, Bradford, and had to use hydraulic spreaders to cut their way through metal gates into the complex and then through the building's metal doors.
Inside they discovered a compresser on fire on the back of a lorry trailer.
The alarm was raised at 10pm on Monday by people who live in Sydenham Place.
Bradford station crew commander Jarrod Stoney said: “We had to send four of our crew into the single-storey building with breathing apparatus and a large jet hose and called for back-up support from three other stations. If the flames had spread it would have been a totally different job.”
Crews left the scene at midnight today. The cause is not suspicious.