A massive power outage struck Florida Tuesday, knocking out electricity to millions of people and snarling traffic.
A spokeswoman for FPL Group 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 of the state.
Local media said the number of those affected was higher.
"I don't know the cause of the outage," Stone told Reuters, saying authorities were awaiting an update from FPL. "There was a failure within the FPL system," Stone said.
Officials in Washington said there were no signs of a link to terrorism.
"There is no indication of a nexus to terrorism at this time ... we will continue to monitor," U.S. Homeland Security Department spokeswoman Laura Keehner said.
CNN reported that eight power plants were shut down and Fox News said that substation equipment failure caused a domino effect of power plant failures.
Local newspapers said power was out in Volusia and Brevard counties on the state's east coast.
By 2 p.m., parts of downtown Miami appeared to be back to normal operation, including a campus of Miami-Dade Community College and numerous stores and businesses. Traffic lights were out for a short time but appeared to be working again.
The U.S. courthouse complex, which includes a federal prison, experienced only a brief outage and is equipped with backup generators to keep the power flowing, officials said.
An official at the Miami International Airport says the facility is working on a generator backup but that no airline delays were reported.
--Reuters and the Associated Press contributed to this story.