NEW YORK – Power outages that darkened the eastern United States and parts of Canada were not linked to terrorism, and electricity “was starting to come back,” New York Mayor Michael Bloomberg said Thursday evening.

“We will be starting up power in the city,” Bloomberg said. “It will take a decent amount of time, hours not minutes — and nobody can be any more specific than that.”

Bloomberg said the water supply was safe and that there were no reports of any injuries from the cities’ skyscrapers or from the subways underground.

“There is no evidence whatsoever of terrorism,” he added

“We have a careful plan that we’ve rehearsed and practiced,” Bloomberg said, adding that there was no reason to call out the National Guard. He said there were no significant fires and “no criminal activity of any size.” Emergency phone numbers were working, despite the blackout.

Shortly before 5:30 p.m., New York Gov. George Pataki declared a state of emergency.

“Preliminarily we’re looking at this as a possible transmission problem from Canada to the U.S.,” said Pataki spokeswoman Lisa Dewald Stoll. She said the problem appeared to be in Canada, but she had no details.

She said had been in touch with the White House, the federal Homeland Security Department, state power officials and Bloomberg.

Bloomberg said Consolidated Edison, which provides power to the area, was not sure what caused the blackout. He said there would an investigation to determine why it occurred and why it affected the whole system.

“I expect everything to be back to business tomorrow,” Bloomberg said.

He urged New York residents to keep their lights and air conditioners off to prevent power surges when the electricity came back. And, in an effort to calm frayed nerves, he cautioned them to stay cool and drink fluids.

“One of the big risks is that people die because of the heat and lack of water,” he said.

He said the city was setting up emergency shelters for those unable to get back to their homes.

He said subway trains were stopped, but that emergency procedures were working and passengers were being evacuated.

The bridges are closed to inbound traffic, but were open to allow traffic and pedestrians to leave the city.

Asked whether it was wise for drivers to pick up people who had swarmed into the street, Bloomberg said: “This is New York where people get along and it’s probably pretty safe, and I wouldn’t have any qualms about doing it.”

Bloomberg said he was in Brooklyn sitting at a table outside when the outage occurred and he didn’t immediately realize it. He said he found out when somebody tapped him on the shoulder.

He called the outage a “major inconvenience.”

Referring to the terrorist attacks of Sept. 11, 2001, Bloomberg added, “We’ll look back on this as another test of New York.”