• A man died after a tree fell on a home near Greensboro, Florida, the Gadsden County Sheriff's Office said.
• Nine Florida counties have enacted curfews.
• More than 500,000 customers are without power in Alabama, Georgia and Florida.
• Bay County is under a mandatory boil water notice.
• A tornado watch is in effect for much of northern Florida and south and central Georgia until 2 a.m. ET Thursday.
• Arrests have been made after reports of looting in Bay County, Florida, Congressman Neal Dunn said.
Mexico Beach resident Patricia Mulligan said the concrete building she lives in shook and vibrated as the storm's center crossed nearby. She was among an estimated 280 Mexico Beach residents who decided not to evacuate, administrator Tanya Castor said.
When she dared to look outside, Mexico Beach's emerald waters and white sugar-sand beaches were covered in a dark sea of splintered debris, she said. Roofs were torn off homes and the marina was gone. Water levels approached the tops of palm trees.
The devastation reminded her of what she witnessed in 1992 when Andrew hit. And she estimated that it would take the same amount of time to fix the damage -- possibly months or even a year.
"We didn't think it was going to be this bad," she told CNN.
After making landfall near Mexico Beach around 2 p.m. ET, the eye of Michael moved inland over the Florida Panhandle east of Panama City.
Wind gusts blew out windows in homes and office buildings, including the First Federal Bank.
Stores and entire shopping centers that were turned into piles of rubble. Other buildings were stripped of their walls and roofs or ripped apart by downed trees and power lines.
Medical Sacred Heart lost its windows and sustained damage to its roof and exterior walls. The hospital said it is running off of generators and patients have been moved to safe areas of the facility.
Jason Gunderson of the Cajun Navy said flooding and downed power lines made most streets impassible. Further hindering rescue efforts were trees that had crashed into homes. In Lynn Haven, north of Panama City, he described finding one woman curled up in a fetal position in a garage with a tree over her head -- a "very dangerous, sketchy situation," he said.
"It's a sight to see, and very sad. Very horrible," Gunderson said.
Brandon and Sydni Troupe were preparing for the grand opening this weekend of their new Panama City business when Michael hit.
They said they spent the past year renovating a house with new floors, walls and a paint job. They intended to sell children's toys and host family-friendly events, a need they saw in the community. Now, a gigantic tree is lying through their store and they're not sure what to do next.
"I still can't believe it. My mind is still trying to process." Brandon Troupe said.
Across the bay in Panama City Beach, a resort city on the Gulf of Mexico known for its white-sand beach and amusement parks, winds of about 100 mph furiously whipped the trees in the early afternoon and pulled apart homes.
In Florida, 54 shelters are open with a population of nearly 6,700 people. A hurricane warning remains in place from the Alabama-Florida border to the Suwannee River in Florida.
Tropical storm warnings were in effect for parts of Alabama, Florida, Georgia, South Carolina and North Carolina.
Storm surge warnings were in place along the Florida and Alabama coasts.
Up to 12 inches of rain could fall in Florida's Panhandle and Big Bend areas, as well as southeastern Alabama and southern Georgia.
Michael's strength may reflect the effect of climate change on storms. The planet has warmed significantly over the past several decades, causing changes in the environment.
Human-caused greenhouse gases in the atmosphere create an energy imbalance, with more than 90% of remaining heat trapped by the gases going into the oceans, according to the National Oceanographic and Atmospheric Association. There's evidence of higher sea surface temperature and atmospheric moisture, experts say.
While we might not get more storms in a warmer climate, most studies show storms will get stronger and produce more rain. Storm surge is worse now than it was 100 years ago, thanks to the rise in sea levels.
According to Climate Central, a scientific research organization, the coming decades are expected to bring hurricanes that intensify more rapidly, should there be no change in the rate of greenhouse gas emissions.
CNN's Natasha Chen, Dave Hennen, Amanda Jackson, Jamiel Lynch, Paul P. Murphy, Spencer Parlier, Hollie Silverman, and John Sutter contributed to this report.