Customers and employees of Northstar Powersports & Marine are safe after the roof collapsed Friday afternoon.

Six employees and six customers ducked for cover when the roof began to fall as a result of too much snow.

The large building is made of wooden beams and trusses with a sheet metal exterior. Albert Lea Fire Chief and Building Inspector Paul Stieler said the trusses are designed for heavy loads.

He said what caused the roof to collapse was a big snowdrift on the southeast side of the building. It placed too much weight on one side of the trusses that hold up the roof. The result is the side without the snow collapses.

“The differential of weight is so much harder on the trusses,” Stieler said.

Another factor, he said, is the trusses in the Northstar building had wooden gusset plates. Most nowadays have metal gusset plates that can support greater loads.

He urged building owners to check their roofs for big drifts and remove them.

The collapse happened at about 3:23 p.m. Northstar Powersports & Marine is at 2120 Consul St. Craig Stickfort is the owner. He was speaking with his employees, family members and an insurance agent at the site on Friday.

Capt. Mark Roche of the Albert Lea Fire Department said the collapse caused a gas leak. Albert Lea police officers blocked traffic on Consul Street and Prospect Avenue and asked people to evacuate the area until Alliant Energy shut the gas off and the smell of gas wafted out of the building. Alliant Energy also shut off the electricity.

Roche said roof collapses are not common but are more likely to happen when wet snow becomes icy snow.

“We’ve had a lot of wet snow that has frozen,” he said.