Electricity was restored to most homes and businesses by midafternoon Tuesday after a widespread power outage in the Flathead Valley.

The outage that caused traffic jams throughout the valley was due to a power line collapsing near U.S. 93 and Reserve in north Kalispell.

“The transmission lines literally fell and they fell on distribution lines — that’s why it had such a widespread impact,” said Wendy Ostrom Price, spokeswoman for Flathead Electric Cooperative.

It turned out that a clamp that holds the lines tight came off a pole near Home Depot. Later in the day, the same lines were put back up with a new clamp.

The outage impacted 10,000 electricity customers, including businesses, through most of Kalispell, north to Big Mountain, Columbia Falls, Hungry Horse and West Glacier, west to the Kila and Marion areas, and south to the Lakeside and Bigfork areas.

The outage caused traffic to back up throughout most affected areas. For a time, traffic heading south on Whitefish Stage Road (rerouted from U.S. 93) was backed up for a mile.

The only areas that seemed to remain with power were the east side of Kalispell and Evergreen.

Ostrom Price said the outage was reported at 11:56 a.m. and, shortly after 1 p.m., power had been restored to Glacier Park International Airport, along U.S. 93 north of Kalispell and to traffic lights in the downtown Kalispell area. Kalispell Regional Medical Center also had power restored early.

At 2:15 p.m., Ostrom Price reported that power had been restored to most of the utility’s members throughout the region.

“The bulk is back. We still have some out here and there,” Ostrom Price said at midafternoon. “It was anywhere from an hour to two hours, depending on where you were, that it took to restore.”

Several schools, including Kila, Smith Valley and schools on Kalispell’s west side, were without power during the outage.

At Kila School and at Peterson Elementary School off Meridian Road in Kalispell, the outage hit during lunch, but with help from emergency lanterns and propped-open doors, students had enough light to finish their meals. The lunch rooms at both schools also are gymnasiums, and neither has windows.

Smith Valley School was lucky, secretary Charmaine Stappler said.

“Basically we have enough windows that generally there’s plenty of light in the building,” she said.

The school also had a store of emergency flashlights and backup batteries, which kept the computers and phone working throughout the hourlong outage, Stappler said.

As soon as school staffers learned the outage would last more than a couple of minutes, they called for portable toilets — “just in case,” Stappler said. They arrived at the school just as the power came back on.

Staff members at Kalispell Middle School used emergency flashlights and cell phones to direct students from class to class, secretary Jane Radel said.

The school’s bells operate on a different system, so they rang as usual, and staff members helped students navigate the dark halls until the power returned at about 1:15 p.m.