New York Gov. Andrew Cuomo slammed electricity company Con Edison as thousands of people were without power Sunday night amid dangerously hot weather.

"We've been through this situation w ConEd time & again & they should have been better prepared—period," Cuomo tweeted.

About 46,000 New York City customers were without power at 9 p.m. EDT because of the persistent heat and high power use just one week after a transformer fire turned off the lights for nearly 75,000 people. The majority of Sunday's scattered blackouts were in the boroughs of Brooklyn and Queens.

Con Edison restored power to about 13,000 people in southeast Brooklyn, according to a statement released at 1 a.m. EDT Monday, but 40,000 remained without electricity.

Cuomo urged residents to check on their neighbors, especially the elderly, who are at increased risk of heat-related illnesses. New York deployed state police, generators and light towers to provide support, he tweeted.

Deja vu:Power restored after partial New York City blackout leaves thousands without electricity

Con Ed said it reduced voltage by 8% in affected areas to maintain service as repairs were made. The company continued to urge power conservation, such as by turning off non-essential appliances. Before the heat wave began, power company officials warned outages may reoccur as people ramp up their air conditioning.

New York City Mayor Bill de Blasio tweeted that the “accumulated heat and strain from the past few days has built up in the electrical equipment.” The city had directed office buildings to set thermostats no lower than 78 degrees through Sunday to reduce strain on its electrical grid.

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The high hit 95 degrees in New York City on Saturday, leading officials to cancel a Times Square commemoration of the 1969 moon landing and an outdoor festival featuring Women's World Cup soccer star Megan Rapinoe and musician John Legend.

Contributing: The Associated Press