HELENA, Mont. (AP) — A power outage affected at least 12,000 customers throughout Montana’s capital Thursday, darkening traffic signals and public buildings and delaying a women’s basketball game being attended by 19 busloads of elementary school students.

The outage that began shortly before noon and left many areas of the city of 32,000, along with neighboring East Helena, without power for up to an hour.

Northwestern Energy spokesman Jo Dee Black said a “transmission issue” was responsible.

The outage temporarily closed the public library and delayed tip-off for a scheduled noon women’s basketball game between Carroll College and the College of Idaho. A loud cheer came from about 2,200 elementary school students attending the “field trip game” when the power was restored.u

The lights went out in the Lewis and Clark Public Library soon after children’s story time ended, and staffers escorted about 30 people out as a safety precaution, library public services manager Lisa Skelton said.

“We wrote down what books they took,” she said.