Scores of firefighters battled a blaze that left an Oxfam warehouse badly damaged.
Ten crews, four of which were support teams, were sent to tackle the fire, which broke out at an industrial estate in Huddersfield yesterday.
West Yorkshire Fire and Rescue Service said the warehouse was "100% involved" in the fire and a structural engineer had been called because the building "was showing signs of collapse".
The single-storey building in Beck Road measures 55m by 40m and is home to Oxfam Wastesaver, which sorts thousands of tonnes of donated clothes and textiles.
Twenty propane canisters were found at the scene by firefighters but were not involved in the fire.
One crew, from Wakefield, remained at the scene early today, with another team set to relieve them at 8am.
A fire service spokeswoman said: "We're still putting a lot of water on it. Anything that's got large-scale packed-up clothes is going to burn."
The cause of the fire has not yet been established.