Hurricane Michael's battering waves swamped streets and docks and shrieking winds splintered trees and rooftops. The most powerful hurricane on record to hit Florida's Panhandle left wide destruction and at least one person dead and wasn't nearly finished on Thursday as it crossed Georgia toward the Carolinas, still reeling from epic flooding in Hurricane Florence.Authorities said at least one person has died, a man killed by a tree falling on a Panhandle home. Search and rescue crews were expected to escalate efforts to reach hardest-hit areas and check for anyone trapped or injured in the storm debris.A day after the supercharged storm crashed ashore amid white sand beaches, fishing towns and military bases, Michael was no longer a Category 4 monster packing 155 mph winds. Downgraded to a tropical storm early on Thursday over south-central Georgia, it continued to weaken but was still menacing the Southeast with heavy rains, blustery winds and possible spinoff tornadoes.The National Hurricane Centre in Miami said the eye of Michael was about 48km south-southwest of Macon in central Georgia at 00:00 on Thursday. The storm had top sustained winds of 112 kph and was moving to the northeast at 27 kph.After daylight on Thursday residents of north Florida would just be beginning to take stock of the enormity of the disaster.Damage in Panama City near where Michael came ashore on Wednesday afternoon was so extensive that broken and uprooted trees and downed power lines lay nearly everywhere. Roofs were peeled away, sent airborne, and homes were split open by fallen trees.Twisted street signs lay on the ground. Palm trees whipped wildly in the winds. More than 380 000 homes and businesses were without power at the height of the storm.Vance Beu, 29, was staying with his mother at her home, Spring Gate Apartments, a complex of single-story wood frame buildings where they piled up mattresses around themselves for protection.A pine tree punched a hole in their roof and his ears even popped when the barometric pressure went lower. The roar of the winds, he said, sounded like a jet engine."It was terrifying, honestly. There was a lot of noise. We thought the windows were going to break at any time," Beu said.Sally Crown rode out Michael on the Florida Panhandle thinking at first that the worst damage was the many trees downed in her yard. But after the storm passed, she emerged to check on the cafe she manages and discovered a scene of breath-taking destruction.'Aggressive' search and rescue efforts underway"It's absolutely horrendous. Catastrophic," Crown said. "There's flooding. Boats on the highway. A house on the highway. Houses that have been there forever are just shattered."A Panhandle man was killed by a tree that toppled on a home, Gadsden County Sheriff's Office spokesperson Anglie Hightower said.But she added emergency crews trying to reach the home were hampered by downed trees and debris blocking roadways. The debris was a problem in many coastal communities and still hundreds of thousands of people were also left without power.Governor Rick Scott announced afterward that thousands of law enforcement officers, utility crews and search and rescue teams would now go into recovery mode. He said "aggressive" search and rescue efforts would get underway."Hurricane Michael cannot break Florida," Scott vowed.Michael sprang quickly from a weekend tropical depression, going from a Category 2 on Tuesday to a Category 4 by the time it came ashore. It forced more than 375 000 people up and down the Gulf Coast to evacuate as it gained strength quickly while crossing the eastern Gulf of Mexico toward north Florida. It moved so fast that people didn't' have much time to prepare, and emergency authorities lamented that many ignored the warnings and seemed to think they could ride it out.In Panama City, plywood and metal flew off the front of a Holiday Inn Express. Part of the awning fell and shattered the glass front door of the hotel, and the rest of the awning wound up on vehicles parked below it."Oh my God, what are we seeing?" said evacuee Rachel Franklin, her mouth hanging open.Based on its internal barometric pressure, Michael was the third most powerful hurricane to hit the US mainland, behind the unnamed Labour Day storm of 1935 and Camille in 1969. Based on wind speed, it was the fourth-strongest, behind the Labour Day storm (296 kph), Camille and Andrew in 1992.It also brought the dangers of a life-threatening storm surge.In Mexico Beach, population 1 000, the storm shattered homes, leaving floating piles of lumber. The lead-grey water was so high that roofs were about all that could be seen of many homes.'We are in new territory'Hours earlier, meteorologists watched satellite imagery in complete awe as the storm intensified."We are in new territory," National Hurricane Centre Meteorologist Dennis Feltgen wrote on Facebook. "The historical record, going back to 1851, finds no Category 4 hurricane ever hitting the Florida panhandle."The storm is likely to fire up the debate over global warming. Scientists say global warming is responsible for more intense and more frequent extreme weather, such as storms, droughts, floods and fires. But without extensive study, they cannot directly link a single weather event to the changing climate.After Michael left the Panhandle late on Wednesday, Kaylee O'Brien was crying as she sorted through the remains of the apartment she shared with three roommates at Whispering Pines apartments, where the smell of broken pine trees was thick in the air. Four pine trees had crashed through the roof of her apartment, nearly hitting two people.Her biggest worry: finding her missing 1-year-old Siamese cat, Molly."We haven't seen her since the tree hit the den. She's my baby," a distraught O'Brien said, her face wet with tears.