Firefighters are battling a huge blaze at the Littlewoods Pools building, one of Liverpool's most famous landmarks.
Nine fire crews are at the scene of the blaze, which has extended upwards from the first floor of the building, Merseyside Fire Service said.
There are no reports of any injuries.
The five-storey art deco structure on Edge Lane was built in 1938 and was part of the Sir John Moores' Littlewoods empire but has stood empty since 2003.
However, just over 12 weeks ago plans were announced for a major new complex at the site, including film and TV studios in the building.
The fire service said it was first called at 19:52 BST and were on scene within four minutes, but found the roof well alight.
Crews using breathing apparatus have entered the building to tackle the blaze across an area measuring 200m by 100m and two jets are being used to douse the flames from the outside.
Hoardings which covered the building's windows have been removed to aid the fighting of the fire, which has spread to about 40% of the building, the fire service said.
It said it had received close to 60 calls from members of the public regarding the fire.
The building had recently been sold with a plan to redevelop the site to become a major film and television studio hub, creating 350 jobs.
Twickenham Studios has signed a deal with developer Capital & Centric to create a £50m northern base at the site.
The company has been in talks with Merseyside Fire Service, Merseyside Police and Liverpool City Council about how best to tackle the fire.
Liverpool Mayor Joe Anderson tweeted: "Absolutely heartbreaking news that the iconic Littlewoods Building is ablaze, looks pretty bad at this stage, let's hope and pray it's salvageable."
A police cordon is in place and the blaze is ongoing.
Shortly after 22:00, the fire service reported large plumes of black smoke coming from the building and advised people living in the vicinity to keep windows and doors closed.