By Kevin Murphy
KANSAS CITY, Mo., Aug 7 (Reuters) - A 4-year-old boy was dead and a woman believed to be his mother was missing after flash flooding in central Missouri that closed an Interstate highway on Wednesday and triggered some evacuations.
"It appears they were washed out of their vehicle when it was swept from a small tributary into a larger creek," said Sergeant Dan Crain, a spokesman for the Missouri State Highway Patrol in Rolla, adding that the vehicle had been found.
The identities of the boy and woman, presumed to be mother and son, were not released. Authorities said they had been swept off a county road in their car on Tuesday and a search for them was underway near Waynesville, Missouri.
Heavy periodic rain from late Monday through Wednesday morning caused major flooding in and near Waynesville, about 130 miles southwest of St. Louis, and evacuations of some homes and buildings.
Missouri Governor Jay Nixon declared a state of emergency on Tuesday and on Wednesday he sent 50 military police from the Missouri National Guard to help residents and protect property in flooded areas.
Rains caused a rapid rise in the Gasconade River, flooding parts of Interstate 44 and led to parts of the highway being closed, according to the Missouri Department of Transportation. (Reporting by Kevin Murphy; Editing by Greg McCune, Toni Reinhold)