PENSACOLASarah Harper of Pensacola was driving home with her 4-year-old son Tuesday night when she experienced the scariest moment of her life, with torrents of rain surrounding her."It was coming down in sheets, and there were insane amounts of wind," said Harper, 26. "I've been here for six years, but my grandmother, who is 77, has been here for most of her life and she said outside of hurricanes she has never seen rain like this. It was even worse than Hurricane Ivan."In 24 hours, some areas of the Florida Panhandle received up to 22 inches of rain, the equivalent of about a third of the average annual rainfall in an almost continuous burst. The Alabama coast also was inundated.Residents were plucked off rooftops or climbed into their attics to get away from fast-rising water. Roads were chewed up into pieces or wiped out entirely. A car and truck plummeted 25 feet when portions of U.S. 90 — the Scenic Highway — collapsed along Escambia Bay in Pensacola. Cars were overturned and neighborhoods were inundated, making rescues difficult for hundreds of people who called for help when they were caught off guard by the single rainiest day ever recorded in Pensacola. One Florida woman died when she drove her car into high water, officials said. At the height of the storm, about 30,000 people were without power.Floodwaters closed a 30-mile stretch of Interstate 10 near the Alabama-Florida border, and Gov. Rick Scott declared a state of emergency in 26 counties. Outside a major hurricane, how does so much rain fall so fast with such devastation? • • •Meteorologists call it a Mesoscale Convective System, a cluster of intense thunderstorms that remained strong Monday night over a large portion of the Southeast coast, creating a large pool of cool, stable air, according to the website Weather Underground. This cool air formed its own high pressure system that cut off the flow of moist, unstable air into the Southeast from the Gulf of Mexico on Tuesday afternoon. Instead of flowing northward, that moisture fell in torrents over the Florida Panhandle and coastal Alabama on Tuesday.The results were historic.Daily rainfall records were set Tuesday in Pensacola, 11.13 inches, and Mobile, Ala., 11.24 inches.Pensacola Airport recorded a remarkable 5.68 inches of rain in just one hour ending at 10 p.m. Tuesday night.At the airport, 15.55 inches of rain fell Tuesday before midnight — setting a record for the rainiest single day in the city. By comparison, the airport in drought-stricken Los Angeles has recorded 15.9 inches of rain — since Jan. 1, 2012. Forecasters issued flash flood warnings as early as Friday, yet many people were still caught unaware. • • •The peak hours of flooding were from midnight to 3 a.m., Escambia County spokesman Bill Pearson said. Escambia County firefighters responded to 186 calls for help during that period, Pearson said. Some people had to swim for it.Water started creeping into Brandi McCoon's mobile home near the state line, so her fiance, Jonathan Brown, wrapped up her nearly 2-year-old son, Noah, in a blanket and they swam in neck-deep water to their car about 50 feet away. Then, the car was flooded. "Every which way we turned, there was a big ol' pile of water," she said. Brown called 911, and a military vehicle picked them up. Kyle Schmitz was at his Pensacola home with his 18-month-old son, Oliver, as heavy rain fell during a 45-minute period Tuesday. He gathered up his son, his computer and important papers and left. "I opened the garage and the water immediately flowed in like a wave," he said. "The water was coming up to just below the hood of my truck and I just gassed it." Elizabeth Peaden was at her weekly bunco game Tuesday night, and it wasn't raining on her way there. On her way home, she drove her van through a flooded intersection and got stuck. "I was scared out of my wits. Water started coming in and I wasn't sure what to do," she said. Peaden waded to a nearby American Legion post where she and about 20 other stranded people spent the night sleeping on tables or the floor. The decision to drive was fatal for a 67-year-old Pensacola woman. The Florida Highway Patrol said Betty Faye Word drowned when her vehicle was submerged by floodwaters on U.S. 29 at Tate School Road in Cantonment at 9:20 p.m. Pensacola police Chief Chip Simmons said two vehicles fell 25 feet when portions of the Scenic Highway collapsed. The truck driver was fine, but a woman in a car needed help getting out. Neither had serious injuries, Simmons said. In Gulf Shores, Ala., where nearly 21 inches of rain fell over a day's time, the scene resembled the aftermath of a hurricane. At the Sportsman Marina in Orange Beach, employee J.J. Andrews couldn't believe what she saw out the window. "We've got water up in our parking lots," she said. "Our docks are under water. It's worse than during Hurricane Ivan, is what they're saying. It's crazy." Information from the Associated Press, Pensacola News-Journal and Los Angeles Times was used in this report.