Detroit Mayor Mike Duggan said a power outage put city schools , firehouses , police stations , City Hall and Wayne State University in the dark Tuesday morning . Speaking at a press conference , Duggan said power had been restored to about one third of the customers by 2 p.m . ET and that power probably will be restored to all by the end of the day . The outage affected about 900 locations , including 36 fire stations and 81 city schools , according to the Detroit website . Public schools dismissed students after the power went out . Duggan said the dismissal went smoothly . The mayor said there had been no spike in police or fire calls while power was out . About 18 state troopers helped 78 officers direct traffic at intersections while traffic signals were out of service , he said . Schools and other public buildings should be back in service Wednesday , officials said . The city website said 740 traffic signals were knocked out , but power was not lost for the 911 system . The outage occurred about 10:40 a.m . ET when a Public Lighting Department ( PLD ) power cable and then a circuit breaker failed , he said . The City of Detroit is going through bankruptcy . As part of the process , the city is getting out of the business of running PLD and the utility corporation DTE Energy is taking over , Duggan said . DTE Energy assisted the city in bringing the system back online . `` All we know at this point is that the cable went to ground , which means it grounded itself out , '' said Jerry Norcia , president and chief operating officer for DTE Electric and Gas Storage & Pipelines . `` So it could be a breach in the insulation or it could be many other circumstances that caused that cable to fail . '' Detroit has experienced notable power outages in the past . Just last Sunday , power went out during a professional hockey game at Joe Louis Arena . Detroit 's Comerica Park lost power last year during the American League Championship Series . The outage trapped some people in elevators in several government buildings , and firefighters were trying to free them , fire Chief Dale Bradley said . This outage is n't believed to have affected residences , officials said . Duggan said he 'd earlier asked DTE to focus on those circuits that fail the most and review them . The cable that failed Tuesday was not one that had done so previously , authorities said . The power outage wo n't affect Tuesday night 's professional hockey game , said Todd Beam , Red Wings director of public relations . `` We are back at full power at Joe Louis Arena , '' he said . `` The game will be played as scheduled at 7:30 p.m . tonight . ''
Detroit mayor says he hopes power will be restored by end of day . Power goes out at public buildings . People trapped in elevators in several government buildings . More than 80 Detroit public schools dismiss students early .