MANCHESTER, Md. (AP) — More than 100 young campers sang songs, read stories and prayed in an open-air pavilion, as they did each night at the River Valley Ranch camp. Then, the sky began to darken and a light rain began to fall.

A supervisor at the Christian summer camp decided to cut the evening short Tuesday and, to be on the safe side, get the children to shelter 150 yards away. As the kids filed onto a wooded path toward one of the camp’s main buildings, a storm that Camp Executive Director Jon Bisset said was “the most violent and localized” weather event he’d ever seen, rapidly formed over the hill.