POSTED: Tuesday, June 4, 2013 - 10:00am
UPDATED: Tuesday, June 4, 2013 - 10:08am
WEST ALTON, Missouri (cnn) — Perilous flooding could wreak more havoc along the Mississippi River on Tuesday, a day after hundreds of Missourians scrambled to flee a broken levee.
The Mississippi River at St. Louis has already topped 40 feet -- more than 10 feet above its flood stage.
The river is expected to crest Tuesday.
And more rain is forecast for Kansas, Missouri, Oklahoma and Arkansas over the next several days, CNN meteorologist Indra Petersons said.
While the St. Louis area may not get the heaviest rain, its location -- where the Missouri River dumps into the Mississippi River -- makes it vulnerable to rainwater rushing downstream from tributaries.
In the St. Louis area, murky brown water covered roads and crept all the way to the doors of houses.
Authorities urged about 300 residents to evacuate because of the levee breach in West Alton, Missouri, Colene McEntee of St. Charles County Emergency Management said.
A bridge spanning the Mississippi River -- one that connects West Alton to Alton, Illinois -- was shut down after a temporary flood barricade gave way.
West Alton residents rushed to build a sandbag fortress.
Volunteers told CNN affiliate KTVI they had one goal: build the wall one sandbag higher than the predicted crest.
Just five months ago, the Mississippi River was suffering from a severe drought.
The river's bottom was actually bone dry in Memphis.
Since then, the river has shot up 45 feet.