SAINT PAUL, Minn. — The Saint Paul Fire Department says a roof collapse at the Minnesota State Fairgrounds was caused by a combination of a unique roof design and heavy amounts of snow.

The Cattle Barn building features two distinct roofs, one that’s higher and sits at an angle, and another that’s lower and lies flat.

Firefighters say that unique roofing design led thousands of pounds of snow to land on a small section of roof during Tuesday night’s rain storm.

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“We had sort of an avalanche effect,” St. Paul Fire Department spokesman Roy Mokosso says. “What happened is all the snow that’s accumulated over the last few weeks collected onto the top roof and got pushed down by the rain. It landed on the lower roof below and that’s how the collapse occurred.”

The extra snow put thousands of pounds of extra weight on an already old and stressed-out roof.

The collapse not only damaged the building, which dates back to 1920, but it also damaged dozens of food stands, RVs and trailers stored inside.

“We’re still figuring out what all got damaged during the collapse,” Mokosso says.

Firefighters believe other buildings on the grounds may also be at risk.

"Fair workers are evaluating all their structures and obviously similar buildings are also being looked at. The age of buildings also moves them up on priority lists as well,” Mokosso explains.

At least one roofing crew was on site clearing snow Wednesday.

Mokosso says that may alleviate some of the extra weight on smaller buildings, but when it comes to larger buildings, he says there’s little they can do to prevent a roof from collapsing.

“Buildings like the grand stand have some very high roofs. Short of rappelling somebody off of a helicopter, there’s not much that can be done except for taping off the area and putting up cones,” Mokosso says.

Fair organizers expect to have the Cattle Barn fixed before the State Fair gates open on Aug. 22.

The upcoming Horse Expo also shouldn’t be affected by the collapse.