(CNN) -- Hundreds of people near the Florida-Alabama border were being rescued from floodwaters brought on by Sally on Wednesday and authorities fear many more could be in danger in coming days.
"We had 30 inches of rain in Pensacola -- 30-plus inches of rain -- which is four months of rain in four hours," Ginny Cranor, chief of the Pensacola Fire Department, told CNN's Wolf Blitzer on Wednesday.
Sally has weakened since making landfall as a Category 2 hurricane on Wednesday morning but its devastating toll was visible across Southern states by nightfall.
By Wednesday night, it was a tropical depression, according to the National Hurricane Center. Located about 10 miles northwest of Troy, Alabama, it had maximum sustained winds of 35 mph and was moving northeast at 9 mph. While all watches and warnings have been discontinued, Sally is still causing torrential rain over eastern Alabama and western Georgia.
Pensacola and other parts of Florida and Alabama were submerged by flooding, rivers were approaching dangerous levels and numerous counties were under curfews to keep residents safe.
"We are still in an evaluation and lifesaving recovery mission, and we need to be able to do that job," said Robert Bender, commissioner in Escambia County, Florida.
Sally unleashed up to 30 inches of rain from the Florida Panhandle to Mobile Bay, Alabama, leading to "historic and catastrophic flooding" there and threatening even more communities as it moves north, the National Hurricane Center said.
In Escambia County, which includes Pensacola, at least 377 people have been rescued from flooded neighborhoods, Jason Rogers, the county's public safety director, told reporters in a news briefing.
"It's going to be a long time, folks ... to come out of this thing," Escambia County Sheriff David Morgan said earlier Wednesday, warning there could be thousands of evacuations.
Doris Stiers ventured outside her Gulf Shores, Alabama, beach home to asses Sally's damage Wednesday and found her community changed.
"Looks like a war zone," Doris Stiers told CNN. "Lots of destruction, homes destroyed, roofs gone. I have not had any service, power or internet. Bad night."
Here's where Sally is going next
Sally made landfall as a Category 2 hurricane near Gulf Shores around 4:45 a.m. CT with sustained winds of 105 mph.
The slow pace of the storm -- now around 7 mph -- was unleashing a damaging deluge across Alabama and the Florida Panhandle on Wednesday evening. Some areas already have collected more than 24 inches of rain and could receive up to 35 inches by storm's end.
Sally is forecast to continue tracking northeastward through Alabama Wednesday night. The center of the storm is expected to move into Georgia and South Carolina on Thursday.
A section of Pensacola's Three Mile Bridge is missing
A barge had slammed a portion of the structure, known to locals as the Three Mile Bridge, on Tuesday and caused the damage, Brad Baker, Santa Rosa County's public safety director, said Wednesday in a Facebook video.
"Anybody who uses the Three Mile Bridge, just know it's going to be a while before you get to use that again," Baker said.
Baker said crews are working to catch the barge that caused damage before it hits something else.
A flood emergency and a half million with no power
Floodwaters have turned streets into rivers in Pensacola. and at least eight rivers in southwest Alabama and the western area of the Florida Panhandle are expected to reach major flood stages late Wednesday, the National Weather Service office in Mobile tweeted.
The weather service had declared a flash flood emergency for "severe threat to human life & catastrophic damage from a flash flood." The warning zone covers parts of coastal Alabama and the Florida Panhandle, including Gulf Shores and Pensacola.
Power has been knocked out for more than 500,000 customers in Alabama and Florida alone, utility tracker PowerOutage.us reported.
Rainfall totals of 10 to 35 inches are possible from Mobile Bay to Tallahassee, Florida, forecasters say.
Sally came ashore 16 years to the day that a Category 3 Hurricane Ivan struck roughly the same areas.
Sally's slow forward speed is expected to continue through Wednesday as it turns to the north and then northeast, taking with it strong winds and more flooding potential.
Central Alabama and central Georgia could eventually see 4 to 12 inches of rain, with significant flash flooding possible. Parts of the Carolinas could receive 4 to 9 inches of rain by later in the week.
Mandatory evacuations were ordered for much of the coast and low-lying areas from Mississippi to Florida, and shelters opened to accommodate evacuees.
Florida Gov. Ron DeSantis said "pretty much any body of water in Northwest Florida" could see a rise in levels over the next few days because of Sally.
"There is going to be a lot of a lot of property damage," DeSantis said in a news briefing Wednesday. "When you see downtown Pensacola, you see three feet of water there, that's going to affect probably every business that's in downtown Pensacola -- there's just no two ways about it."
Damage and flooding in Alabama
In Alabama, the floor and walls on the 16th floor of a hotel on the northern rim of Mobile Bay groaned as Sally made its way ashore.
The building shook as if in the throes of an extended, low-grade earthquake, and sturdy windows seemed poised to pop out, a CNN team there said.
In Orange Beach, Alabama, water flowed at least a foot deep along the exterior walls of tourist shops, video taken from a moving boat by the United Cajun Navy before sunrise Wednesday shows.
At the shore, a boat sat on its side not far from an upended refrigerator, according to the footage, posted to Facebook.
Daylight revealed another loose boat had come to rest against an Orange Beach condominium building, a photo from resident Rich Florczyk showed. Flooded streets were littered with downed tree limbs and other debris.
On Dauphin Island, south of Mobile, "we've got trees down all over the place ... (and) electricity has been shut off to the entire island," Mayor Jeff Collier said Wednesday morning.
As wind and rain whipped even before midnight, enormous trees already had been felled west of Mobile.
Workers in raincoats endured Sally's bands as they worked alongside a digger truck to move thick piles of branches at Campfire and Ponderosa drives, CNN affiliate WALA reported.
Similar scenes unfolded around the same time -- still about six hours before Sally came ashore -- in midtown Mobile and across Mobile Bay in Fairhope, Alabama.
Sally is the fourth hurricane to make landfall in the US this year -- the most by this point in a year since 2004. It also is the eighth named storm to make landfall in the US, the most by September 16 on record.
CNN's Michelle Krupa, Hollie SIlverman, Gary Tuchman, Ed Lavandera, Gabe Ramirez, David Williams, Brandon Miller and Alisha Ebrahimji contributed to this report.