Texas forecasters issued a series of early-morning warnings about “life-threatening flooding” along the Guadalupe River.

The flash flood in Kerr County has killed at least 51 people, including 15 children. Authorities have not disclosed the official count of missing persons apart from the children from Camp Mystic, a Christian summer camp along a river in Kerr County, from where most of the dead bodies were recovered.

Some experts say staff shortages might have complicated forecasters’ ability to coordinate responses with local emergency management officials.