Arsonists have struck again at the old Kirklees College building in Huddersfield.
Firefighters were called to the building in Portland Street on Tuesday night and found paper had been deliberately set alight in one of the rooms.
The fire was quickly brought under control but fire officers say it could have been much worse had the blaze spread.
It is the latest in a series of arson attacks at the old college, which is due to be demolished.
Earlier this month two rooms on the ground floor of the three-storey building were gutted in a more serious blaze, and firefighters had to battle to stop the fire spreading.
Six teams using breathing apparatus went into the smoke-filled building.
It took them over an hour to bring the blaze under control.
VIDEO from the last attack below
There have also been fires at the site in February and April.
After the fire earlier this month, Watch Commander Chris Bell, of Huddersfield fire station, appealed for the public to be vigilant.
He said the building is full of old furniture, and cables, and it could be very dangerous if a fire spreads.
Most of the college is due to be demolished to make way for a new development called Trinity Central which may feature a health care facility, veterinary practice, retirement flats and a Lidl supermarket.
A large part of the site is occupied by what was the former Huddersfield Infirmary.
Oldham-based Wiggett Construction Group are behind the huge development and have obtained permission for the new Lidl store.
That will mean the 1970s college buildings which have been targeted by the arsonists and burglars will be demolished.