A rapid-fire line of tornadoes has torn across Indiana and Ohio.
The twisters were packed so closely together that one crossed the path carved by another.
The storms strew debris so thick that at one point emergency crews had to use snowploughs to clear a major road.
At least half a dozen communities from eastern Indiana through to central Ohio suffered damage, according to the National Weather Service.
Some five million people were without power in Ohio alone.
Towns just outside Dayton, Ohio, took some of the heaviest hits.
The National Weather Service tweeted that a “large and dangerous tornado” hit near Trotwood, Ohio, eight miles north-west of Dayton.
About 40 minutes after that tornado cut through, the weather service tweeted that another one was traversing its path, churning up debris densely enough to be seen on radar.
The aftermath left some lanes of Interstate 75 blocked north of Dayton.
Trucks with ploughs were scraping tree branches and rubble to the side to get the major north-south route reopened, according to Matt Bruning, a spokesman for the Ohio Department of Transportation.
Trying to clear the debris in the middle of the night is a difficult task, complicated by darkness and downed power lines, Mr Bruning said.
Crews were also clearing debris in two other counties north-west of Dayton.
In Montgomery County, which includes Dayton, Sheriff Rob Streck said many roads were impassable.
The Montgomery County sheriff’s office initially said the Northridge High School gym would serve as an emergency shelter in Dayton but later said it was not useable.
An Indiana town was also heavily damaged by storms, including reports of two tornadoes.