TAMPA, Florida (CBSNewYork/AP) -- Hurricane Irma weakened into a tropical depression Monday night as it moved north, while rescuers in its soggy, wind-battered wake mobilized to reach victims and learn the full extent of the damage.
The storm engulfed nearly the entire Florida peninsula, wreaking havoc from the state's southernmost point up to the Georgia line, from the Atlantic coast to the Gulf side. Late Monday night, the tropical depression was over the Georgia-Alabama state line.
What remains of the storm is expected to pass through northern Georgia and northern Alabama, then later through the Tennessee Valley in the days to come.
Around midday, Irma's center began pushing into Georgia, where a tornado spun off by the storm was reported on the coast, and firefighters inland had to rescue several people after trees fell on their homes.
The U.S. National Hurricane Center says it's expected to weaken to a tropical depression by Tuesday afternoon.
As CBS News' Meg Oliver reported, water was still spilling into beachfront neighborhoods around Florida Monday.
Near the southwest tip of the state, Marco Island saw major damage after Irma made landfall there. The storm surge was receding at last there on Monday.
In Jacksonville, the St. John's River was flooding downtown.
"This is potentially a weeklong event with the water, tides coming and going," said Jacksonville Mayor Lenny Curry.
Neighbors helped rescue neighbors in Jacksonville, as historic floodwaters raged through the streets.
"It's bad now, it's going to get worse as we go into high tide," said Jacksonville EOC Meteorologist Angie Enyedi.
The Jacksonville Sheriff's Office warned residents along the St. Johns River to "Get out NOW."
"If you need to get out, put a white flag in front of your house. A t-shirt, anything white," the office said on its Facebook page. "Search and rescue teams are ready to deploy."
Nearby Atlantic Beach also took a beating from fierce winds and floods. Most roads are unpassable for anyone who tried to ride out the storm on the barrier island.
Streets were also left underwater in Naples.
In Big Pine Key, mobile homes lay on their sides and roofs were missing.
Some were thankful it was not worse.
"We've got the walls up," said a Big Pine Key resident named Mike. "We can always rebuild it. "
Irma damaged some roads in the Florida Keys, making them impassable. The storm roared ashore there Sunday morning with winds of 130 mph.
Residents hoping to get back home were forced to wait.
"I'm not frustrated, I'm just upset this is happening to people, to us," said Pete Garcia of Key Largo. "It's not frustrating, just sad."
Irma also caused devastation in Florida City near the Keys, reducing buildings to rubble.
One of the biggest obstacles for people returning home to survey the damage was downed trees blocking roads.
In Coral Gables, near Miami, fallen trees made streets look like jungle, and damaged power lines buzzed.
"We have about 65 percent of the state out without power," Florida Gov. Rick Scott during a news conference Monday. "It's going to take us a long time to get power back. I've been talking to the utilities. I'm having daily calls from the utility to get the power back on."
And while Miami escaped a direct hit from Irma, the storm still caused widespread flooding and damage.
In South Beach, CBS2 was turned away by police because there was too much damage. So CBS2's Jessica Layton came to the downtown business district – where black garbage bags and palm fronds littered the streets.
Miami business owner Angela Casachagua said she was extremely tired after the experience of the hurricane, but "after coming here and seeing all this, we have to fix it."
Casachagua heard there was still electricity on the street where her family business has been for two decades -- two blocks from the downtown waterfront. She thought they would be OK.
But when she opened the doors, she saw wet tiles crumbled on flooded floors after parts of the ceiling collapsed.
"We are going to be here 20 years," Casachagua said in tears. "Nothing like this has ever happened."
Parts of Miami's usually thriving business district saw three feet of flood water. Elsewhere, hurricane force winds ripped awnings hang from buildings next to palm trees that split and fell across the sidewalk.
In the Miami neighborhood of Coconut Grove, boats were left tossed on top of each other.
And when night came in Miami on Monday, it was sticky and hot outside. With no power, Nelson Sanchez did not have much to do but sit outside the house, hope for a breeze and make the best of it.
"We have a lantern, turns into a flashlight," Sanchez said.
Sanchez, originally from Hoboken, moved to Miami a few years ago to be closer to his 84-year-old mother. He can't get over what the neighborhood looks like.
"Really was bad -- 80 or 90 mph gusts; very scary," he said.
Under the hot sun in the Fort Lauderdale area, homeowners cut up and clear trees that hit their homes. CBS 2 flew Drone Force 2 over the streets where drivers are dodging debris.
Police were checking IDs before allowing people over the bridge to the barrier island, where parts of the streets are beneath sand.
One woman originally from New York said she and her boyfriend were packing up and trying to get back to their home in Delray Beach to see what's left.
"I'm just hoping the house is OK. If not, we'll have to make other plans to move and relocate," she told CBS2's Layton. "I've been through Hurricane Sandy, had to stay in a hotel for three months and I did not enjoy it so hoping everything is OK and praying it will be all right."
Business owners who felt spared are breathing a sigh of relief.
"We really expected like a Cat 3 or 4 to hit us," said Fort Lauderdale business owner Michele Penrod. "We got very lucky, very fortunate."
And those who did have a mess to clean up were just glad their families were safe and sound and able to help.
"Luckily, we're fine," Casachagua said. "We're healthy and we're strong, and we'll come back."
The full breadth of the damage statewide remained unclear, with communications and travel cut off by high winds and flooding. Search crews planned to go door-to-door in the hard-hit Keys to check on residents.
Along the Gulf Coast, two manatees became stranded after Irma sucked water out of Sarasota Bay, located in Florida's Manatee and Sarasota counties. Several people posted photos of the mammals on Facebook amid reports rescuers later dragged them to deeper water.
President Donald Trump approved a disaster declaration for Florida, opening the way for federal aid. And Florida's governor activated all 7,000 members of the Florida National Guard, and 10,000 guardsmen from elsewhere were being deployed.
Irma once was the most powerful hurricane ever recorded in the open Atlantic, a Category 5 with a peak wind speed of 185 mph. For days, forecasters had warned Irma was taking aim at the Miami area and the rest of Florida's Atlantic coast. But then Irma made a westward shift and lost some of its punch while crossing Cuba's northern coast — just before a crucial turn into Florida's Gulf Coast.
In the Caribbean, at least 24 were people were killed during Irma's destructive trek. In Cuba, the storm swamped Havana's iconic seawall, pushing water nearly a third of a mile inland.
(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)
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