TEMPE, Ariz. (AP) -- Power has been restored to parts of Arizona State University's main campus in Tempe. The cause of the outage hasn't been determined yet, but school officials say power was fully restored around 11:30 a.m. Tuesday. Parts of ASU's main campus were without power for several hours Tuesday morning, but most classes weren't disrupted. The outage began about 7:40 a.m. and left about 18 buildings without power including the ASU Bookstore, the Fulton Center and the Sun Devil Fitness Complex. It's the second power failure on the Tempe campus in less than a month. Over winter break in January, leaking water caused a shutdown to about 20 percent of the campus.