New Delhi, July 11 -- Hundreds of people were trapped in high water along the rain-swollen Black River as flash flooding unleashed by torrential rains from a wave of thunderstorms struck the Ozark Mountains in rural southeastern Missouri on Friday, officials said.

Missouri Governor Mike Kehoe declared a state of emergency in flood-stricken regions to ease coordination between state and local agencies and hasten disaster assistance.

According to State Highway Patrol Sergeant Eddie Young, National Guard teams in Black Hawk helicopters flew some 200 stranded people to higher ground on Friday afternoon from Camp Taum Sauk in Lesterville, Missouri, about 100 miles (160 km) south of St. Louis.

About half of the evacuees from the summer youth...