Flash floods struck parts of Maryland on Sunday, including a suburb of Baltimore that had suffered similar devastation two years ago.
Dramatic video from Ellicott City showed cars being swept away by raging waters along its historic Main Street.
Rescuers struggled to reach people trapped in their homes, but so far the authorities have said they had no immediate reports of injuries.
Locals posted on social media photos and video of the turbulent floodwaters and people trapped in buildings.
Maryland Governor Larry Hogan has declared a state of emergency in the flood-stricken area.