MIAMI -- A transmission glitch at a West Miami power substation knocked out electricity yesterday to as many as 3 million people across the state, halting public transportation, snarling traffic and cutting the air conditioning in homes from Key West to Daytona.
Neither crime nor foul play was involved, making the blackout mostly just "a massive inconvenience," Miami-Dade County Mayor Carlos Alvarez said.
"It's a matter of just a cascading effect," he said.
But on a day when the mercury climbed high into the 80s, the loss of air conditioning and refrigeration in the heart of the workday added to the stress of life in overdeveloped South Florida, already troubled by nightmare traffic and ubiquitous construction.
Miami Fire Rescue responded to numerous calls from people trapped in stalled elevators, including one heavily pregnant woman, said Lt. Ignatius Carroll. None suffered any injury beyond a few anxious moments, he said.
Office workers in high-rise buildings in Miami, Fort Lauderdale, Orlando and other cities were evacuated as a precaution, some having to walk down 30 or 40 flights of stairs before discovering that the elevators were working again.
For most, the outage lasted less than 30 minutes. Florida Power & Light, the state's largest electrical utility, said service had been fully restored by nightfall. FP&L; put the number affected by the outage much lower than state and county officials, saying only about 800,000 lost power.
Traffic lights in western suburbs of Miami continued to malfunction after most power was restored, forcing police to deploy to key intersections to direct traffic by hand through the evening rush hour. Long backups formed on the busy expressways that traverse South Florida.
Fender-benders at intersections without working signals clogged major thoroughfares and blocked freeway off-ramps, causing miles-long rivers of crawling cars.
The Federal Energy Regulatory Commission, which has responsibility for electricity grid reliability, said it wants to know whether there were any violations of federal grid reliability rules.
The sporadic outages spanned 300 miles of the peninsula but appeared to be concentrated in the southeast portion of the state, including Miami.
Initially, a FP&L; spokesman said its nuclear plant caused the outages to about a fifth of Florida's population. But the utility's nuclear spokesman, Dick Winn, later said grid problems caused both reactors at the Turkey Point plant to shut down. Two coal-burning power plants at Turkey Point also shut down, authorities said.
Power went out with an audible squeal shortly after 1 p.m., compelling hospitals, airports and other essential services to fire up their backup generators.
At Miami International Airport, the reserve power source kept the flow of travelers moving - at least those who made it through the surrounding congestion.
"I was certain we would miss our flight," said Lydia Rodriguez, fanning herself with her ticket as she and her husband waited to enter the security screening. They had spent more than an hour driving to the airport from the stricken Doral area, normally less than a 15-minute trip.
Concessions were on reduced power through the 25-minute outage at the airport while the generators ran, depriving air travelers of cold drinks and hot sandwiches because servers couldn't use the automatic dispensers or heating ovens, said Gerald Mejia-Fugon, a cashier at the Au Bon Pain bakery cafe.
The power outage was triggered by a malfunction at a Florida Power & Light transmission facility just west of here.
"The system trips itself to protect the reactors. It did what it was supposed to do," Nuclear Regulatory Commission spokesman Kenneth Clark said in Atlanta of the Turkey Point shutdown. "This was not a nuclear problem. It was a problem in the electrical grid system."
There were never any safety concerns during the outage, he said.
Another NRC public affairs officer, Holly Harrington in Rockville, Md., said it could take as long as 24 hours to restart the nuclear reactors and return the power supply to normal.
Miami's MetroRail and MetroMover train networks ceased running for about a half-hour in the early afternoon but were back in service well ahead of the evening commute.
Miami-Dade and Broward school districts held up bus service for many homebound students to avoid their traveling while traffic lights were out of service.
Carol J. Williams writes for the Los Angeles Times. The Associated Press contributed to this article.