Tens of thousands of people were without power in Manhattan on Saturday evening, ConEdison said.

There were 45,000 customers without power in New York, most of them in Midtown Manhattan and the Upper West Side, the utility company said.

Mayor Bill de Blasio, who was campaigning for president in Iowa, said it appears the outage was the result of a mechanical problem in the electrical grid.

"This appears to be something that just went wrong in the way that they transmit power from one part of the city to another," he told CNN. "It sounds like it is addressable in a reasonable amount of time."

Times Square's billboards are black as people fill the street.
Times Square's billboards are black as people fill the street.
Thomas Urbain/AFP/Getty Images
People use their phones as flashlights.
People use their phones as flashlights.
Michael Owens/AP
Pedestrians looks at their cellphones in midtown Manhattan.
Pedestrians looks at their cellphones in midtown Manhattan.
Michael Owens/AP
Radio City Music Hall is dark during the blackout.
Radio City Music Hall is dark during the blackout.
Erik Pendzich/Shutterstock
An entrance to the C and E trains at the 50th Street Subway Station is dimly lit.
An entrance to the C and E trains at the 50th Street Subway Station is dimly lit.
Michael Owens/AP
People sit inside a bar during the power outage.
People sit inside a bar during the power outage.
Marie Barbier/CNN
Dark buildings along a dark street are seen near the Times Square area.
Dark buildings along a dark street are seen near the Times Square area.
Jeenah Moon/Reuters
Con Edison workers stand around a barricaded transformer cover.
Con Edison workers stand around a barricaded transformer cover.
Catherine Koppel/Reuters
People are evacuated outside Row NYC hotel.
People are evacuated outside Row NYC hotel.
Jeenah Moon/Reuters
A convenience shop is closed.
A convenience shop is closed.
Haiyun Jiang/CNN
A man directs traffic on 8th Avenue and West 58th Street.
A man directs traffic on 8th Avenue and West 58th Street.
David Dee Delgado/Getty Images
The Upper West Side of Manhattan is in the dark. The city's fire department was responding to numerous transformer fires, the first of which occurred in Manhattan on West 64th Street and West End Avenue, officials said.
The Upper West Side of Manhattan is in the dark. The city's fire department was responding to numerous transformer fires, the first of which occurred in Manhattan on West 64th Street and West End Avenue, officials said.
Alan Reeves via AP
People walk along a dark street near Times Square.
People walk along a dark street near Times Square.
Jeenah Moon/Reuters
A police officer directs traffic in Times Square.
A police officer directs traffic in Times Square.
Johannes Eisele/AFP/Getty Images
A view of the Hell's Kitchen neighborhood shows buildings in darkness.
A view of the Hell's Kitchen neighborhood shows buildings in darkness.
Linda N/Reuters
A train sits out of service at Penn Station.
A train sits out of service at Penn Station.
Jeenah Moon/Reuters
Buildings near Columbus Circle are dark.
Buildings near Columbus Circle are dark.
Marie Barbier/CNN