Power Restored in Detroit After Outage Closes Schools, Snarls Traffic

— -- Power has been fully restored to Detroit customers, hours after a cable snafu knocked out power to much of the beleaguered city, the mayor's office said this afternoon.

The outage create plenty of hassles for city residents, as students were dismissed from schools early, traffic lights were knocked out and even one firehouse was unable to open its doors.

Detroit Mayor Mike Duggan said the failure was caused by the aging infrastructure of a city that just emerged from bankruptcy. He said when one power cable failed, power was rerouted to a second cable which also failed. In order to not overload the power grid, Duggan said the entire system was shut down.

The cable belonged to Detroit Public Lighting, according to Homeland Security officials. Detroit Edison provides power to much of the Detroit area, but the older downtown grid is operated by the Detroit Public Lighting.

The mayor warned Detroit residents similar blackouts could continue to happen as the electrical grid is fully revamped and Detroit Edison takes over full operation of the city.

Multiple municipal buildings including the City County Building, the Joe Louis arena where the Detroit Red Wings play, the Detroit City Airport were affected according to ABC News affiliate WXYZ-TV in Detroit.

The Detroit Fire Department said all firehouses used backup generators and radios to respond to calls, according to Lt. Theresa Halsell. One firehouse, was unable to open its doors, officials said.

Halsell said a few people were temporarily stuck in elevators, but they were quickly evacuated and Duggan praised firefighters who carried some people down stairs.

Nearly all Detroit public schools, 87 of 97, lost power. All schools dismissed students early due to the power outage.

Traffic lights were out and 100 officers were dispatched to the busiest intersections to keep traffic moving safely.

At Wayne State University classes initially kept running even though a couple dozen buildings were without power, according to Wayne State University spokesman Rashida Williams.

Wayne State University student Kristin Shaw, 24, said she was in her first class when the lights started to flicker.

"The flood lights went on and he kept teaching," Shaw said of her professor. "He was discussing infrastructure failures...He made an infrastructure joke and how funny it was" the power was out.

Shaw said the building she was in was without power but that classes continued.

All classes on the main campus and all evening events were later cancelled, according to the Wayne State University twitter.

ABC News' Tom Llamas, Jack Date and Jonathan Newman contributed to this report.