Frank Murphy Hall of Justice (above) is among sites evacuated after the 10:30 a.m. widespread outage. (Photo by Jamal Bransford of WDIV)
Update: 5:26 p.m. -- The mayor's office issued this statement: Crews from the Department of Public Lighting are reporting that power has been restored to all customers affected by today's cable failure.
Update, 4:26 p.m. Tuesday -- The mayor's office issued this statement:
The Detroit Public Lighting Department, working closely with DTE, is reporting that approximately 75% of the city's public lighting grid is back online. We expect that power will be restored to the vast majority of customers by 7:00 p.m. tonight.
Update, noon: The outage results from a Detroit Public Lighting cable failure, according to Roop Raj of Fox 2 News. "Experts have isolated problem and are working to fix now," he tweets.
The Frank Murphy Hall of Justice regained power shortly after noon, media reports say.
Computers crashed, elevators stopped between floors and lights went dark in government buildings throughout downtown Detroit at 10:30 a.m. Tuesday as a widespread power outage hit the Detroit Public Lighting grid.
Buildings that were evacuated include Joe Louis Arena, Coleman A. Young Municipal Center, the Frank Murphy Hall of Justice and some Wayne State University sites, Holly Fournier reports at The Detroit News.
Roughly 100 customers of the notoriously balky Detroit Public Lighting (DPL) municipal electric grid are affected, Fox 2 News says.
Detroit Fire Department crews worked to extricate people trapped in elevators throughout downtown, according to scanner reports on the department's emergency frequency. They and medics also were bringing down wheelchair users and others with handicaps who were on darkened upper floors of government buildings.
DFD/DPD: Emergency Operations Center (EOC) has been activated and advises those required to report.
— DetroitScanner.com (@DetroitScanner) December 2, 2014
Also affected are traffic signals, streetlights, the People Mover, Detroit Receiving Hospital, the Detroit Instituteof Arts, police precincts and fire stations -- all of which are served by DPL. The hospital, police and fire crews -- including dispatchers -- were using gasoline-powered generators, media reports say, though electric-powered city fuel pumps can't be use to refill them -- causing concern.

Detroit Public Schools reportedly are being dismissed.
Fournier writes:
Lights flickered in the buildings around 10:30 a.m. before the power went out. At the municipal building, staff, employees and visitors used flashlights to navigate basement hallways. Hundreds of people streamed out of the building as authorities announced the Coleman A. Young Municipal Center would be evacuated and shuttered for the day. . . .
At Frank Murphy, the elevators were out and deputies directed crowds toward the jammed stairwells. A group of people were stuck in an elevator on the sixth floor. Some people also were stuck in another elevator for a few minutes.
The outage also stopped the Robert Bashara murder-for-hire trial. This marks the second time a power outage has impacted the Bashara trial, which was delayed when a power outage occurred during a preliminary exam last summer.
-- Alan Stamm