About 5,800 Idaho Falls Power customers were without electricity for about three hours Friday.
Idaho Falls Power Customer Service spokesman Van Ashton said the probable cause of the outage was a Mylar balloon that was found tangled in some of the power lines.
All the power has been restored, Ashton said.
The outage affected the northwest side of the city, including the downtown area.
The situation gave some students an early weekend.
According Facebook posts from Idaho State University and the University of Idaho, the power outage forced their Idaho Falls campuses to close for the day.
Also affected by the outage is the A.H. Bush Elementary School.
The school district decided to send students home after lunch beginning at 12:30 p.m. School officials were trying to notify all the parents.
Buses will be provided for students who normally ride the bus. Other students will be walking home early.
This isn't the first power issue for the area Friday.
A downed power line caused a traffic disruption on U.S. Highway 20 on Friday morning.
Crews rushed to Exit 311 near St. Leon Road at 6 a.m., where the line was down.
Bonneville County dispatch says the highway reopened just before 7 a.m.