More than 500 downtown Des Moines customers of MidAmerican Energy were without electricity for about 80 minutes this morning beginning at 8:22 a.m.

It’s not yet known what caused the outage, said Geoff Greenwood, MidAmerican Energy spokesperson. Crews were working to find the cause, he said.

The outage appeared to be located on the eastern portion of downtown, although Greenwood didn’t have specific boundaries of the outage. Among the 559 customers affected by the outage were the Polk County Administration Building at 111 Court Ave., Ligutti Tower at 555 Fifth Ave., the Des Moines Civic Center at 221 Walnut St., Hy-Vee and the apartments above it at 420 Court Ave., the Plaza condominiums at 300 Walnut St., Confluence on Third Apartments at 103 S.W. Third St., and the Science Center of Iowa at 401 W. Martin Luther King Jr. Parkway.

Also affected were the R&T Lofts at 717 Locust St. As of publication time, power had not yet been restored to the building.