FARGO, North Dakota (CNN) -- Parts of Bismarck, North Dakota's capital, sat underwater Thursday, a precursor to what could happen in coming days if rivers in the state continue to rise toward historic levels and overflow.
The Southport section of Bismarck was swamped with a few inches to several feet of water, North Dakota emergency officials said.
The National Weather Service issued a foreboding forecast for the state, saying that many rivers were at flood level -- the worst being the Red River, which was predicted to have a historic 41-foot crest by Saturday.
The last flood near that level was in 1997 when the river crested at 39.6 feet. The record for the Red River in Fargo, the state's most populous city, was set in 1897 at 40.1 feet, according to the National Oceanic and Atmospheric Administration.
North Dakota was not the only state bracing for dangerous weather.
Blizzardlike conditions were forecast for parts of Texas and Oklahoma, according to the National Weather Service. A tornado ripped through a small town in southern Mississippi early Thursday, damaging buildings and trees, officials said. And severe thunderstorms Thursday left 18,000 residents in East Baton Rouge Parish, Louisiana, without power.
In North Dakota, hundreds of volunteers filled sandbags and scrambled to build dikes, and officials evacuated thousands of residents from affected areas. Watch North Dakota brace for record flooding »
One of the people racing against the river was Jennifer Sondag from the Fargo area, who has been documenting and sharing her stories on iReport.com.
"Driving around town is almost warlike at times," Sondag said. "Things are barricaded, sirens are sounding, people are talking about evacuation plans." iReport.com: Watch Sondag's daily updates on the situation
The threat from the Missouri River caused about 4,000 people to be evacuated Tuesday from an area near Bismarck. On Wednesday, authorities blasted ice jams from the river in an effort to keep it from rising even higher.
But the Red River posed the gravest threat, officials said.
"Nobody that's alive today has ever seen it at 41 feet," said Fargo Mayor Dennis Walaker. "They need to take this extremely seriously."
Walaker said it's only smart for city officials and residents to think about worst-case scenarios, which could include a citywide evacuation.
"If they [residents] have people that are infirm or have difficulty getting around, they should consider taking them out of the city" before any evacuation orders, he said.
"If you have kids that are small and so forth, evacuation would scare the tar out of them."
City officials had been hoping that the river would top out at 39 feet, which would mean that their plan of getting all dikes to a 42-foot level would work. But with the 41-foot crest predicted, officials and volunteers will need to add an extra foot on the levees containing the river.
Officials on Wednesday called on volunteers to help out day or night at two locations. Both the North Dakota State University arena, the Fargodome, and a central location will continue operating around the clock, officials said. Watch volunteers heed the call to help »
Earlier Wednesday, emergency crews responded to an upscale neighborhood in the town of Oxbow, along the Red River about 15 miles from Fargo.
Almost all of the 60 or so houses in the neighborhood had been evacuated, but the U.S. Coast Guard used an airboat to rescue nine people, including a man who had climbed a tree to avoid deepening water.
"I know one call came in -- the water smashed through the basement windows and was filling all the way up to the main level," said Cass County Sheriff Paul D. Laney.
Some homeowners had built sandbag dikes around their homes, many of which had been breached. By midafternoon, water was overtaking mailboxes.
A helicopter rescued five adults and an infant in nearby Abercrombie.
Walaker said some arrests had been made to keep people off the dikes because the ice and snow mixture makes the areas on and around them dangerous. Walaker did not elaborate on the arrests beyond saying there were just a few.
Laney offered a stern warning to anyone in the area without a good reason.
"I'm going say it as blunt as I can be: Stay out of our operation area if you don't belong here," Laney said. "I've put an arrest team out up and down the corridor."
He added, "People's lives are at stake. People's houses and properties are on the line."