Firefighters watched over the site in Waterloo Lane in Bramley following a huge blaze, which began at around 8.40pm last night.
David Smith, station commander at Stanningley, said 10 pumps and an aerial appliance had been used to bring the fire under control.
“We’re talking about 50 personnel at its height. It was pretty well alight when they got here,” he said.
“Last night there were fears about smoke. That risk is now diminished.
“We’re in a situation now where it needs to be demolished and that’s not as simple as it seems.”
The gas supply to the warehouse was cut off in the early hours of this morning when workers dug up part of Waterloo Lane.
And work was under way on thiscal afternoon to isolate the electricity supply to the building so that power could be restored to a handful of nearby properties.
Mr Smith said: “It’s a lot like a jigsaw puzzle at the moment. The majority of the roof is in tact, so we’re waiting for them to get the roof down.
“We’ll be here this evening and into tomorrow. When they do start to demolish, there might be pockets of fire that arise again.”
The 28,000 sq ft warehouse with offices was not in use at the time of the fire.
It was being marketed for rental by estate agent Savills.