A small element of young people in Strabane have been blamed for setting fire to a disused factory premises in the Ballycolman Industrial Estate.
The fire was reported to the emergency services shortly after 4.30pm last evening.
8 fire-fighting appliances tackled the blaze for a number of hours last evening- no-one was injured when the building collapsed but police have said that the structure is still in a dangerous condition.
They have asked the public to avoid the area while the cause of the fire is investigated.
Local Councillor Brian McMahon said efforts would be made to secure the site in the short-term given the major danger it now presents, particularly to any young person attempting to enter the unstable buildings.
He said there is a small element of young people who have been making life a misery for residents in the wider Ballycolman area and this arson attack is just the latest incident in a long line of anti-community activities.