Firefighters were called to a sixth arson attempt on a former Halifax bed factory in three months on Sunday.
Police, firefighters and Calderdale Council are working to stop the arsonists who have been targeting the former Dorlux bed factory on Shroggs Road, Lee Mount.
Since end of July fire crews have been called to the site on the Elizabeth Industrial seven times.
On the first occasion it was an accidental secondary fire involving controlled burning onsite.
The following four occasion were secondary fires (rubbish) which are suspected to have been set alight deliberately around the premises.
Then on Thursday, October 9, shortly before 5.15pm a fire spread to a building onsite and required three engines to attend. Again this is thought to have been started deliberately.
However, the most recent fire at 6pm on Sunday has seen a multi-agency effort to try and stop the fire bugs.
District Commander for Calderdale Martyn Greenwood said: “We are working closely alongside the owner of the premises, the police and Calderdale Council’s Environmental Health department to resolve the issues.”
A total of seven different crews attended the fire on Sunday- the largest yet - which and saw huge flames lighting up the sky over Halifax.
Eyewitness Mark Bolton, who Tweeted in a photograph of the fire, said: “After spending the afternoon collecting funds and selling firefighter charity calendars in Leeds I looked out of my window and saw smoke billowing up in the distance.”
Crews from Halifax, Elland, Illingworth and Brighouse attended the incident and used four breathing apparatus, two hose reels and a positive pressure ventilation fan to tackle the flame which were raging through the ground floor of the property.
A West Yorkshire Fire Service spokesperson said a thorough search of the building was done for anyone sleeping rough, but the building was empty.
The fire caused smoke and heat damage to the rear of the building. Smoke also blew on to the A629 Ovenden Road.
Relief crews from Hunslet, Bradford and Dewsbury attended the incident at various points.
Firefighters eventually left the scene just before 1am the following morning.