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A damaging storm system that spun off multiple tornadoes from Louisiana to Florida killed at least three people and critically injured at several others as it moved through the South, with more twisters likely to come Wednesday along the Atlantic coast.

Two people were killed as a tornado touched down near the Sugar Hill RV Park northwest of the town of Convent, Louisiana. At least 30 people were treated at hospitals, seven of them in critical condition, said Brandon Keller, a spokesman for the St. James Parish Sheriff's Office.

A third person was killed in Lamar County, Mississippi, county Coroner Cody Creel told NBC News, identifying the man as Harris Dale Purvis, 73. The National Weather Service said radar indicated a possible tornado at the scene, where a mobile home was destroyed.

The system then crawled into southern Alabama and northern Florida late Tuesday.

A tornado injured six people and seriously damaged three buildings at an apartment complex in Pensacola, Florida, said Amanda Taft, a spokeswoman for the Escambia County Board of County Commissioners. The extent of the injuries wasn't immediately known, Taft told NBC News.

The National Weather Service reported that a car was blown off Interstate 10 near Brent in Escambia County and that vehicles were overturned on other roads. The Florida Highway Patrol closed a 26-mile stretch of I-10 in Escambia and Okaloosa counties and urged motorists to stay home and off the roads.

NBC station WPMI of nearby Mobile, Alabama, reported that trees were also uprooted onto other roadways, blocking traffic and delaying the arrival of emergency crews. About 9,200 customers were without power in the Panhandle, Gulf Power said at 11:15 p.m. ET.

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Behind the storm, the governors of Louisiana and Mississippi declared emergencies as recovery efforts got under way.

Kenner officials report damage from apparent tornado https://t.co/cMjBojAFk4 pic.twitter.com/86LmvBs2VE — wdsu (@wdsu) February 23, 2016

Almost 17,500 customers remained without power across Louisiana at 10:30 p.m. ET, Louisiana's seven main electric utilities reported. The state Office of Homeland Security and Emergency Preparedness activated its crisis action team to coordinate responses.

At a news briefing Tuesday night, Willy Martin Jr., sheriff of St. James Parish, Louisiana, described a scene of massive destruction at the RV park in Convent — "almost like something exploded."

About 300 people live in about 160 trailers on the site, and at least one remained unaccounted for Tuesday night, Martin said. He urged residents to call in and report that they're OK.

After visiting the scene Tuesday night, Gov. John Bel Edwards marveled at the "awesome destructive powers that tornadoes have."

"It is a jumbled mess," Edwards said. "These travel trailers were picked up, moved a considerable distance and really blown apart, torn apart. There are heavy-duty F350 pickup trucks back there that were just mangled."

Edwards called it a "minor miracle" that only two people were killed.

Assumption Parish Sheriff's Deputy Robert Martin told NBC News that one person was reported injured amid moderate to severe damage from a tornado that destroyed a parish water tower. The parish emergency management agency issued a notice for all residents to boil their water as a safety measure.

"It was just raining like a regular day, and then we heard, like, a whistle, like a train, and that's when everything started," said Kenneth Rodrigue of Belle Rose in Assumption Parish.

"It blew out a couple of big windows on my mom's house. Lots of roofs came off of people's houses," Rodrigue told NBC News. "It's bad. Real bad."

No injuries were reported in the New Orleans suburb of Kenner, where a tornado damaged a few cars in a lot west of Louis Armstrong New Orleans International Airport, according to the National Weather Service. No flights were directly affected, but the airport said Tuesday afternoon that some delays and cancellations were possible because of the bad weather in general.

In Ascension Parish, Louisiana, at least eight homes and businesses were damaged, said Meredith Conger, a planning officer with the parish's emergency management agency.

Latest @NWS radar shows massive storm that spun off tornadoes heading into Mississippi. pic.twitter.com/hlwHFYJxe3 — Alex Johnson (@MAlexJohnson) February 23, 2016

In addition to the five confirmed tornadoes, the National Weather Service was reviewing reports of three others, and government offices in 15 parishes closed early to get people home before the dangerous weather hit, Louisiana Administration Commissioner Jay Dardenne said.

The weather system is expected to move east into the Carolinas down to Florida on Wednesday, with the possibility of more tornadoes, forecasters said.

"This is one of the better tornado setups that we've had in this part of the country for a while," said Ari Sarsalari, a meteorologist for The Weather Channel.

.@NWS hazard map showing tornado (tan) and flood (green) threats moving southeastward through Wednesday. pic.twitter.com/qRZ9iOMqAr — Alex Johnson (@MAlexJohnson) February 23, 2016

In Atlanta, the South's biggest city, and areas north, "ingredients continue to be coming together for a potentially significant severe weather event," including isolated tornadoes, overnight into Wednesday, the National Weather Service said Tuesday evening.