At least one firefighter is dead after a fire at a vegetable packing plant in Atherstone on Stour, near Stratford-upon-Avon, in Warwickshire.
The fire on an industrial estate was tackled by up to 100 firefighters from Warwickshire; Herefordshire and Worcestershire; and the West Midlands.
Firefighters had to come to terms with the news that one of their colleagues had been killed and three others were missing.
Some 16 fire engines were called to the incident which started on Friday evening. Police said they are treating the blaze as suspicious.
Firefighters cut their way through a door at the warehouse. The building was still alight on Saturday morning and suffered a partial collapse during the blaze.
A search of the building for the missing firefighters is to get under way as soon as colleagues can enter the building.
Large parts of the building's roof collapsed during the blaze. The warehouse is understood to be located on the site of a disused airfield.
The blaze was eventually extinguished on Saturday after burning for more than 12 hours.
Fears that four firefighters have died prompted a flag to be flown at half mast at Stratford-upon-Avon fire station.