A deadly flash flood has killed at least six people and forced thousands to flee after the Guadalupe River surged more than 22 feet overnight, breaking its banks and flooding several towns in Kerr County, Texas.

“Heavy rainfall caused the Guadalupe River to rise rapidly,” reaching a near-record height of 34 feet, officials reported. Kerrville, Hunt, and Ingram were hit hardest, with entire homes and even an RV park swept away by the current.

One Kerrville family—two parents and their two children—remains missing. “The area where the family’s home once stood is now a vacant lot,” according to WOAI-TV. Authorities suspect it was completely washed away.

A flash flood emergency was declared by the National Weather Service after nearly 10 inches of rain fell overnight. Residents were urged to “seek higher ground immediately” as the flooding was described as “dangerous” and “potentially life-threatening.”

Rescue operations are ongoing, with several people pulled from submerged RVs and campers. The emergency alert remains in effect for Kerr and nearby Kendall County until at least 2 p.m. Friday.