POST FALLS - An outdoor event tent was blamed for more than 9,000 Post Falls residents losing power for nearly an hour late Monday afternoon.

The event tent came into contact with a transmission line along Chase Road west of River City Middle School, said Debbie Simock, Avista spokeswoman.

Simock said how the tent touched the line on a relatively calm afternoon was being investigated.

"Something did blow it into the transmission," she said. "This is another example of why it's important to make sure things are securely anchored so that they don't become airborne."

The location where the tent was found is at the top of an incline where it can often be breezy. Poles that attach the tent to the ground were dangling from the tent on the line. A graduation party in that area was held or being planned, so onlookers said that may have been from where the tent came.

At the peak of the event, 5,025 Avista customers and 4,400 KEC members were without power, starting at 4:06 p.m.

"It was a large outage for us," said Erika Neff, KEC spokeswoman. "Our members were affected because our substation in that area feeds through the Avista transmission system."

The outage affected most of Post Falls, from Poleline Avenue to south of the Spokane River.

Neff said all of KEC's members had their power restored by 5 p.m. As of 5:30 p.m., 1,871 Avista customers remained without power, but the company was rapidly reducing that number, Simock said.