CADDO GAP, Ark. — Floodwaters that rose as swiftly as 8 feet an hour today rushed into a remote Arkansas valley early, killing at least 20 people, many of them campers who became trapped by a devastating wall of water.

Dozens more were missing and feared dead.

Heavy rains caused the normally quiet Caddo and Little Missouri rivers to climb out of their banks during the night.

Around dawn, floodwaters barreled through the Albert Pike Recreation Area, a 54-unit campground in the Ouachita National Forest that was packed with vacationing families who were probably still asleep when their tents began to fill with water.

Two dozen people were hospitalized. Authorities rescued 60 others.

The water quickly began to recede, and anguished relatives pleaded with emergency workers for help finding more than 40 missing loved ones.

The water poured through the valley with such force that it overturned RVs, peeled asphalt off roads, and swept away tents and their occupants.

Gov. Mike Beebe said the death toll could rise.