Andy Byford, the chief executive of the New York City Transit Authority, said he was in Williamsburg, Brooklyn, when he heard that the lights were going out in Midtown Manhattan. He and Veronique Hakim, the authority’s managing director, went to the subway control center and oversaw the rescue of 2,875 passengers from three D trains and two A trains, Mr. Byford said.

With power still flowing to the third rails but not to the system’s signals, the trains had to be guided forward to the next station, where riders stepped off onto platforms. Mr. Byford said none of them required medical assistance. He said five people were rescued unharmed from an elevator at the 34th Street-Hudson Yards station.

“This was the biggest incident that we faced on my watch,” Mr. Byford said.

At Con Edison’s control room in Midtown, Mr. Cawley said, trouble was first detected Saturday evening when circuit breakers popped opened and “de-energized” the West 49th Street substation. The disruption quickly affected five networks that distribute electricity within particular neighborhoods, including Midtown West, Rockefeller Center and Times Square. Power was lost in an area that stretched south from 72nd Street between the Hudson River and Fifth Avenue. Eventually, a sixth network, serving the area around Pennsylvania Station, also failed.

Mr. Cawley said some of the utility’s equipment might have been damaged, but “the grid is sound.” He said the last time there had been a similar failure that did not have an external cause was 13 years ago.

The mayor praised Con Edison for its speedy restoration of service, but Gov. Andrew M. Cuomo, a Democrat, was more critical. Mr. Cuomo said in a radio interview on Sunday on WINS-AM (1010) that he would have state investigators conduct an independent review of the failure, which he called unacceptable.

“You lose power, chaos is right around the corner,” Mr. Cuomo said.

The blackout shut down 26 Broadway shows, but all of them had returned to their regular schedules by the Sunday matinee, according to the Broadway League, a trade association.