NEW YORK CITY (AP) — A power outage cast darkness across dozens of blocks in New York City early Friday, as many people in the city were still without electricity in the aftermath of Tropical Storm Isaias.

Con Edison said in a tweet that it was aware of a “brief service interruption” in Manhattan and that a problem on its transmission system caused three networks to lose power.

The utility added that crews have been working around the clock to restore power across the city due to the tropical storm that battered the East Coast earlier this week.

Live video showed few lights across Manhattan, including parts of the Upper East Side, Upper West Side and Harlem, around 5:15 a.m., WABC-TV reported. Some customers said their power was back by 6 a.m.