Flooding from torrential rain killed at least one person in Ellicott City, Maryland, and at least two people are missing after floodwaters swept through the town's historic downtown.
Ellicott City was pounded by almost 15cm of rain in two hours late on Saturday (local time), sending the Patapsco River out of its banks, officials said.
Howard County Executive Allan Kittleman said the flooding in Ellicott City, about 56 km north east of Washington, was worse than that from Hurricane Agnes in 1972.
"I don't believe there's ever been a flood and the devastation that we've had overnight in Ellicott City," he said in an interview with Baltimore's WBAL NewsRadio.
He said the body of one woman was found in the Patapsco River overnight.
County spokesman Andy Barth said at least two people were missing.
Kittleman said there had been severe damage to the historic downtown Main Street area.
Governor Larry Hogan declared a state of emergency, as did Kittleman. The declarations allow aid to be released more quickly.
Firefighters rescued about 120 people from the high waters, including 80 from a bar, Howard County said in a statement.
Emergency workers were also dealing with a water main break and a natural gas leak.
Television footage showed a downtown street collapsed, power poles down, mud-covered roads and cars tossed atop one another.
The heavy rain was part of a system of thunderstorms that moved through the region.