The origin of a massive fire that tore through a disused office building has been deemed "unknown", as the damage was too extensive for a root cause to be established. 

The large blaze, on Darlington's Haughton Road, and near Bannatynes Gym and Health Club, had firefighters working to extinguish it late into the night on Friday (May 26). 

Flames erupted from the building around 9 pm on Friday night, with plumes of smoke visible across Darlington. 

For more quality journalism, subscribe to The Northern Echo for £1.50 a week here. 

The Northern Echo:

The disused offices are understood to have been the site of a £1.7 million cannabis farm, which was discovered by police in March, though County Durham and Darlington Fire and Rescue Service (CDDFRS) were unable to determine if this has an impact on the blaze.

A spokesperson for CCFRS said: "On Friday, May 27, just after 9pm, our control room received a call about a fire at a building on Haughton Road in Darlington.

"On arrival, our crews found a large building, known to be empty, well alight.

"During the course of the incident, several fire service vehicles from Darlington, Bishop Auckland, Newton Aycliffe and Spennymoor attended the scene including flexi duty officers and both Aerial Ladder Platforms.

"Our crews worked together from outside the building to extinguish the fire. The last fire engine left the scene just after 2 am on Saturday 28th May.

"The cause of the fire is unknown. If you have any information in relation to this incident, please call Firestoppers anonymously on 0800 169 5558 or report online by visiting www.firestoppersreport.co.uk."

Read next:

The Northern Echo:

A spokesperson for Durham Constabulary confirmed that they were also in attendance at the fire, and helped with the closure of Haughton Road. 

The incident saw the listed building blackened and burnt, sustaining intensive damage during the ferocious blaze. 

Meanwhile, some eyewitnesses reported seeing ash falling over nearby streets.