Teams of firefighters continued battling the blaze overnight into Monday after it ignited at the single-storey building on the Junction 41 industrial estate near the M1 between Leeds and Wakefield on Sunday afternoon.
At its peak more than 80 firefighters from across the region fought the flames which a spokesperson for West Yorkshire Fire & Rescue Service said had “completely destroyed” a building that extended to approximately 50 metres by 60 metres.
Three fire engines, plus an aerial appliance, were still at the scene yesterday to dampen the smouldering debris and crews were expected to continue the operation last night.
West Yorkshire Police said they had ruled out any suspicious circumstances while the Health & Safety Executive said it was aware of the incident and that it was making “initial enquiries”.
The Yorkshire Evening Post understands that the main bakery is largely undamaged, and that Morrisons has been operating deliveries to its stores as normal from its nearby depot.
Morrisons confirmed that the fire involved its premises on Stephenson Way, which are operated as Rathbones Kear Ltd, and that staff were working inside when the fire broke out.
A spokesman said: “All colleagues were evacuated quickly and safely.”
Some members of staff were treated for smoke inhalation but no one was seriously injured.
Huge plumes of big smoke could be seen coming from the site for miles around.