Miami ? Millions of Floridians sweated. Restaurant owners tossed out their food. Motorists battled each other even more than usual. And all for something that should have been just a blip on the electrical grid.

An equipment malfunction in a substation near Miami on Tuesday started a domino effect that power officials had stopped but were still struggling to understand by late afternoon.

The relatively minor problem somehow caused two power distribution lines to be disabled between Miami and Daytona Beach. In response, Florida Power & Light’s Turkey Point nuclear plant south of Miami stopped operating around 1 p.m., Nuclear Regulatory Commission spokesman Kenneth Clark said.

The result was aggravation and confusion across south and central Florida. Gerson Anzueto said AM radio stations were down when he tried to figure out what was going on, and it wasn’t until his daughter called him a half hour later from Guatemala that he got some information.

“How is that she had more information in Guatemala than I did?” said Anzueto, who works at a Miami restaurant. He scrambled to swipe patrons’ credit cards to make the most of his register’s 15 minutes of battery life.

Looking out at the street, Anzueto said he was shocked that many drivers failed to obey basic traffic laws, such as stopping at an intersection where lights weren’t working. “People weren’t acting responsibly,” he said.

Up to 3 million people – about a fifth of Florida’s population – lost power at various points during the afternoon, though there were no safety concerns at the nuclear plant. And while many areas were hit hard, the outages were short lived and only about 20,000 people lacked electricity during the evening commute home. Most of the evening outages were due to bad weather, not the grid problem, officials said.

Florida Power & Light was trying to determine what caused the equipment failure and a fire at the substation, but the company said it was not the kind of problem that should have created the widespread blackouts.

Grid problems caused both Turkey Point reactors to shut down, said the utility’s nuclear spokesman, Dick Winn.

“All the safety systems worked just like they were supposed to and both of those units are in stable condition right now,” he said. Clark, of the NRC, agreed the plant’s safety was not in question.

The outages had no connection to terrorism, Homeland Security Department spokeswoman Laura Keehner said. Miami-Dade County Mayor Carlos Alvarez said the outages were technical, not criminal.

Florida emergency management officials said the outages cut power to 2 million to 3 million people during the heat of a day that saw temperatures reach the 80s.