A levee keeping a swollen river from inundating a southeast Missouri town cracked in at least one place Tuesday, but water pouring through the breech was unlikely to force the further mass-evacuation of homes in the area, authorities said.

Crews were also looking into reports of another breach in the levee protecting Poplar Bluff and the surrounding area along the Black River from major flooding, police officer Daron House told The Associated Press. He said officials were planning to evacuate more homes, but that he didn't know how many.

The breach happened southeast of Poplar Bluff in an area that's not heavily populated, Butler County Sheriff Mark Dobbs said Tuesday. The water was pouring into a drainage ditch along a road, and even it if topped the ditch, was unlikely to cause enough backflow to threaten Poplar Bluff homes upstream, he said.

The levee is holding back a river swollen by a powerful storms moving through the Midwest that dumped several inches of rain on the Mississippi and Ohio river valleys over the past week. The storms spawned at least one tornado in Arkansas Monday night that killed four people and carved a wide swath of destruction through the town of Vilonia.

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Kasey Medley, right, stands on the front porch of her flooded home with her friend Erica Cass Tuesday in Poplar Bluff, Mo. (Jeff Roberson/Associated Press)

Poplar Bluff deputy police chief Jeff Rolland said Tuesday that more than 15 centimetres of rain fell on the town on Monday, bringing the four-day total in the area to 40 centimetres and causing the Black River to pour over the levee in 30 places from Poplar Bluff to the downriver town of Qulan.

More rain expected

More showers and thunderstorms were expected in the area on Tuesday, giving crews that worked overnight to sure-up the levee no rest.

Rolland said street department workers hurriedly filled small boats with sandbags overnight and were able to sure up a vulnerable section of the levee in Poplar Bluff, a town of 17,000 residents that is 130 miles south of St. Louis.

Crews rescued 59 people in 1 1/2 hours late Monday after water spilled over the dam.

A full-scale levee breach could force the evacuation of some 6,000 homes from Poplar Bluff to Qulin and destroy or severely damage 500 homes in Poplar Bluff and its outskirts, Rolland said. Already, 23 small businesses in the area's flood plain have taken on water, he said.

The hotels in town filled up quickly, and 300 people took shelter at the Black River Coliseum, the town's 500-seat concert venue, Rolland said. No deaths or serious injuries have been reported.

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An American Airlines aircraft is pictured through a broken window at Lambert-St. Louis International Airport on April 23, after the airport was hit by a tornado. (Reuters)

Families forced to flee their homes Monday watched as murky floodwater began creeping into their yards and homes. If the levee were to give way, many of those homes would be left uninhabitable. Sandbagging wasn't an option — the river, spurred on by 25 centimetres or more of rain since last week, simply rose too quickly.

"By the time we realized what was happening it was too dangerous to sandbag," Butler County presiding commissioner Ed Strenfel said.

Severe storms that began early last week have hammered the nation's midsection without letup.

Again Monday, powerful storms ravaged Missouri, Arkansas, Kentucky, Texas, Tennessee and other states.