Firefighters were called to a suspected arson in a vacant former government office building.
Five appliances from Runcorn, Widnes, Lymm, Penketh and Warrington, descended on East Lane House at the junction of East Lane and Crown Gate in Runcorn at 3.13pm on Sunday. Cheshire Fire and Rescue Service (CFRS) said the blaze was on the ground floor and initially crews tackled the flames from outside with hose reel jets and wearing breathing apparatus.
A CFRS spokesperson said six firefighters entered the building including to remove debris and check adjoining rooms. They said the suspected cause was arson.
