BOULDER — The University of Colorado today sent out an emergency text-message alert to students for the second time in three days.

This morning, CU alerted students to a 4 1/2-hour power outage in several residence halls, classrooms and administrative buildings.

Power was out from about 2:45 a.m. to 7:30 a.m., affecting roughly 3,967 students 15 halls.

It made some late for classes.

"They had to shower in the dark and get themselves ready with no power available," said Deb Coffin, assistant vice chancellor for student affairs and executive director of campus housing.

The dining staff arranged a continental breakfast in place of the normal full breakfast.

But most students were waking up about the time the power was restored, Coffin said.

CU-Boulder's new text-messaging system, called RAVE, was used to alert some 6,000 subscribers.

It was used for the first time Monday when a man with a history of mental illness stabbed a student on campus.

John Morris, director of Facilities Operations, said the outage was caused by an electric cable failure.

Affected residence halls included Baker, Libby, Farrand, Brackett, Crosman, Cockerell, Reed, Hallett, Willard, Cheyenne Arapaho, Andrews, Buckingham, Smith and the Kittredge West Halls. Farrand, Libby and Kittredge Commons dining operations also were impacted.

Other buildings affected by the outage, which was less critical because of the time of day the outage occurred, included Regent Administrative Center, 914 Broadway and 924 Broadway, Wolf Law Building, Fine Arts, Environmental Design, Coors Events/Conference Center, Ketchum, Imig Music Building, Fiske, Planetarium and the Sommers-Bausch Observatory.