Police are searching for a group of teenagers who were seen leaving a former school building moments before a blaze broke out.
Four teenage boys were seen at the former Habergham High School in Kiddrow Lane on Sunday evening before the blaze which was tackled by seven fire engines from across East Lancashire.
Crews from Burnley, Padiham, Nelson, Hyndburn, Colne and the Command Support Unit from Preston tackled the flames using two main jets and hosereels and wearing several sets of breathing apparatus. A spokesman for Lancashire Police said the fire had been started inside the two storey building at around 9pm.
The spokesman said: “The teenagers were seen leaving the area but unfortunately we do not have a description of them.
“But we would like to hear from anyone who saw the teenagers on the site or anything else suspicious.”
Originally built as Burnley Girls’ High School in 1951 it survived until 1981 when it was merged with Burnley Grammar School to create Habergham High School.
It became empty in 2006 when Burnley’s other five secondary schools moved into purpose built facilities as part of the £250m Building Schools For The Future programme.
The building has been earmarked for demolition but before this can happen Lancashire County Council needs to get permission from the government to dispose of the site. The future development of the site is still under discussion with borough planners.
Calls have been made to make the building secure as there has been several incidents of vandalism and in June last year Kieron Simpson (15) almost died when he fell 20 foot off a roof while playing on at the disused building with friends.
It is believed the building contains asbestos so the demolition process will have to be handled by experts.
Anyone with information about the fire is asked to ring 101 and quote reference number 1282.