UPDATE 1-Power out to millions in Florida

(Adds details, previous New York)

MIAMI, Feb 26 (Reuters) - A widespread power outage struck south Florida on Tuesday because of a shut-down at a nuclear reactor, knocking out electricity to millions of people and snarling traffic across the state, officials said.

A spokeswoman for FPL Group Inc FPL.N said the company's Turkey Point nuclear reactor in Florida shut down due to the loss of off-site power but would not elaborate on the cause of the outage.

Mike Stone, a spokesman for the Florida Division of Emergency Management, said the blackout affected two to three million people in south Florida and as far north as the Tampa area.

“I don’t know the cause of the outage,” Stone told Reuters, saying authorities were awaiting an update from FPL.

In Washington, a U.S. Homeland Security Department spokeswoman said there were no signs of a link to terrorism in the power outage.

There is “no indication of a nexus to terrorism at this time ... we will continue to monitor,” agency spokeswoman Laura Keehner said.

Local newspapers said power was out in Volusia and Brevard counties on the state’s east coast.

On Aug. 14, 2003, New York City and much of the Northeast and parts of the Midwest United States suffered a blackout that affected 50 million people. It was widely seen as the worst blackout in North American history.

That outage stranded hundreds of thousands of commuters and trapped subway riders underground in New York City, where thousands of people spent a hot night sleeping on sidewalks or walking miles in the darkness to reach their homes.

Reporting by Scott DiSavino, Tom Brown and Randall Mikkelson; Editing by Frances Kerry