Crews are frantically working to save 16 million seedlings after the roof collapsed at a Canfor tree nursery Friday morning in Prince George.

Structural support of the roof over the cold storage cooler at the J.D. Little Nursery gave way, causing two walls to fall over. No one was inside when the roof came down and no one was injured.

Tom Lewis, Canfor's vice president of woodlands, says the company is now trying to find temporary homes for the seedlings, which are worth about $3 million.

"Currently, our understanding is none of the trees are lost. Walls are off the side of the building, and we're just working on a plan to safely remove those trees."

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WorkSafeBC has given its permission to demolish Canfor's J.D. Little Nursery in Prince George. (Canfor)

He says it's warm weather — not cold — that could potentially damage the trees, as they were being stored at sub-zero temperatures. However, once the seedlings start to thaw, further freezes can damage the roots.

"This is part of our normal process, to start to thaw these trees out. So they would be stored in winter a little cooler than that," Lewis said.

"They also can't be too cold, because that impacts on the roots. And then as we move further into the springtime, of course, we start to increase the temperatures."

Lewis said workers are building a temporary shelter to keep the seedlings warm until permanent repairs can be done.

Two cave-ins in two days

He said it's unclear what caused the roof to collapse, as the building was engineered to withstand a large amount of snow.

WorkSafeBC has given permission to Canfor to demolish the building which is the second casualty of heavy, wet snow in Prince George in two days.

On Thursday, the roof over the pool area of a house caved in. No one was home at the time and there were no injuries in that cave-in either.

Prince George Fire Chief John Lane says both incidents appear to be connected to the freeze-thaw cycle, resulting in significant snow and ice buildup. He said it was fortunate that nobody was injured.

"We generally respond with the anticipation of that it could be a very serious event and fortunately, in both of these cases, there's been no entrapment and no compromise to any critical structures, such as gas lines, or electrical lines or anything like that," Lane said.

With files from the CBC's Marissa Harvey