The worker was inside at 1 a.m., working on the ice surface when he noticed some unusual sounds, said spokesperson Joanne Gaudet.
"We did have the one employee inside who was inside flooding the rink at the time," she said. "He heard a couple of pops and bangs and then the one side of the facility collapsed.
He got out and then a portion of the roof came down.
The sheer force of the collapse blew out an entire wall, she said.
The employee was back at work this morning she said.
"They are a little shaken up. More of a kind of 'Wow' moment for them because, absolutely, it could have been so much worse," she said. "We're all grateful for that for sure."
The town shut down main streets around the arena, saying the structure is still unstable.
The quonset-type structure, which is about 30 years old, shares a gas and power line with the multiplex next door, forcing the closure of that building for up to two days.
Gaudet said the town can't comment on the cause until structural engineers examine the site.
Like much of central Alberta, the town has received far more snow than usual.
The town has been looking at replacing the facility with a leisure centre so the collapse will likely speed up that process, Gaudet said.
The town is now contacting surrounding communities to find ways to provide ice time for teams and groups who had booked the ice, she said.
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