A series of explosions went off in an underground tunnel at the University of Oregon.
No one is reported injured.
Campus officials said the blasts Monday morning appear related to the electrical system, but they don't yet know the cause.
Campus police spokesman Kelly McIver says there were about five explosions around 10 a.m., followed by a series of blasts for about half an hour. Videos showed puffs of smoke coming from manhole covers.
McIver says fire department personnel were waiting to make sure the power has been shut off before going into an underground tunnel to check the electrical system.
The student health center was evacuated, and McIver said a few buildings are either without power, or have power intermittently.
The incident began just before 10 a.m. on the first day of winter classes.
A university police spokesman told the Register-Guard newspaper the dorms were not evacuated, but police shut down Agate Street between 13th and 15th avenues.
The explosions are being blamed on a likely malfunction in a maintenance tunnel, according to a Register Guard report.
Copyright 2013 KPTV-KPDX Broadcasting Corporation. All rights reserved. The Associated Press contributed to this report.