OSAWATOMIE, Kansas (AP) -- Rivers swollen to record levels by days of heavy rain inched higher in parts of the southern Plains on Monday, keeping thousands of people from returning to water-logged homes.

Crude oil spilling from a refinery into one flooding river in Kansas contributed to the mess and flowed toward Oklahoma, where high water had chased thousands of people from their homes.

Crude oil spilling from a refinery into one flooding river in Kansas contributed to the mess and flowed toward Oklahoma, where high water had chased thousands of people from their homes.

The Kansas National Guard was sent to help with a mandatory evacuation of Osawatomie, a small town in eastern Kansas and one of the hardest-hit communities in the region. The town evacuated 40 percent of its 4,600 residents after two rivers -- Pottawatomie Creek on the town's south flank and the Marais des Cygnes on the north -- rose out of their banks.

"I think the Marais des Cygnes will be OK," Mayor Philip Dudley said. "I'm still concerned about Pottawatomie Creek. It's supposed to get over 49 feet on Monday."

Rain had mostly stopped falling Monday in Kansas, but the National Weather Service extended a flash flood watch for the state's southeast corner