A power outage hit south Napa on Monday morning, leaving Napa Valley College in the dark from shortly after 9 a.m. until almost noon.
Teachers were given the option of canceling classes and some did, said college spokesman Doug Ernst.
Pacific Gas & Electric reported that 1,700 customers were initially affected, with all but 23 restored within four minutes. One of those customers was apparently the college.
Most of the affected customers lived east of Highway 221/Soscol Avenue, said Deanna Contreras, a PG&E spokesperson.
The cause of the outage had not been determined as of noon, she said.