Electricity was out for more than 90 minutes Friday morning in several blocks of downtown Minneapolis, darkening City Hall and police headquarters as well as many office buildings, officials said.

Offices went dark at about 6:20 a.m., and power was restored to all customers at 7:55 a.m., an Xcel Energy spokesman said.

The affected area was mainly east of Marquette Av. and near 5th St. Signal lights were out at many intersections. Motorists took to the courtesy of taking turns going through intersections.

Xcel Energy spokeswoman Patti Nystuen said an electrical vault fire occurred about 11:30 p.m. Thursday at what is known as the CenturyLink building, darkening that location, 215 S. 5th St.

As workers tackled that, "additional problems" forced the utility to "deenergize" several nearby blocks, she said. The utility has yet to provide further details about the subsequent trouble it encountered.

Along with City Hall and police headquarters, affected buildings included the U.S. Bank Plaza and the Star Tribune. Lights stayed on at the Hennepin County Government Center.

Calls to 911 were not affected, said police spokesman Stephen McCarty.

Metro Transit said that light-rail trains kept running as usual. Hennepin County Medical Center is in the area that went dark, but the hospital operated normally, presumably thanks to a backup power source, a hospital spokeswoman said.

Star Tribune staff writer Tim Harlow contributed to this report.

Paul Walsh -- 612-968-2483