Canada Revenue Agency employees will face a backlog of extra work on Monday after a fire at the regional tax centre in Winnipeg forced a weekend shift to evacuate.

Firefighters say they were called to the tax centre on Saturday morning.

Revenue agency spokesman Kevin Lloyd says about 85 people were in the building processing tax returns.

Lloyd says the fire was sparked by contractors who were working at the front entrance and that the flames spread underneath the floor.

He says smoke filled the building, but little damage was done and everyone got out safely.

He says no tax records were damaged but workers won't be returning to the building until Monday.

"As you can imagine, we're getting busier this time of year. It's tax filing season so it's not unusual to have staff that would be working on the weekend," Lloyd said.

The centre handles individual and business returns for Alberta, northern Saskatchewan, Manitoba and large parts of southern Ontario.

Lloyd said the next scheduled shift would have come in Sunday night.

Despite the interruption, Lloyd assured there would be no delays in the processing of returns.

"The building is secure. Everyone's information is secure, but there's two or three hours of lost productivity because of the smoke that was a result of the fire," he said.