Searchers intensified their recovery efforts Monday morning and planned to drain a lake, a day after a deadly tornado tore through the southern Indiana countryside near Evansville, Indiana.
That twister, part of a line of thunderstorms that smashed through the region about 2 a.m. Sunday, killed at least 21 people, 17 of them in the Vanderburgh County mobile home park near Evansville. Four more people died in neighboring Warrick County.
Authorities also are counting as a fifth death the 8-month-old fetus of one of the victims.
More than 200 people were injured.
Related storms caused extensive damage and killed horses at a Kentucky racetrack.
"Mother Nature picked the worst place to drop a tornado," said Vanderburgh County Sheriff Brad Ellsworth. "It's an open field, a mobile home park. There's just nowhere to go."
Searchers Monday will drain a lake adjacent to the mobile home park.
Ellsworth said that while there were a number of people still unaccounted for, authorities did not necessarily believe any victims would be found in the lake.
"We know there is a lot of debris in that lake," he said. "That's why we're going to go ahead and breach that. It's only about 6 feet deep."
Knight Township fire chief Dale Naylor, the incident commander, told reporters that the lake was the last area searchers had to cover. "We wrapped up about 10:30 last night what we consider to be our rescue effort," Naylor said.
"At this time, we don't believe there are any [more] survivors at this point," Naylor said. "We are going to continue this morning with our recovery operations."
Naylor said people who are unaccounted for likely "walked out on their own."
Indiana Homeland Security spokeswoman Pam Bright said 100 of the 320 mobile homes had been destroyed and 125 others had been damaged.
Adam Groupey, deputy director of emergency management for Evansville and Vanderburgh County, said the tornado touched down about 2 a.m. in Henderson County, Kentucky, then crossed the Ohio River and hit the mobile home park before moving into Warrick County.
One resident of the mobile home park told TV station WFIE of Evansville she saw a tornado pick up a car with members of her family in it and toss the vehicle into a tree. Brandi Crawley said no one was seriously injured.
"The damage is very, very extensive," said Chad Bennett, an assistant fire chief in Newburgh, in Warrick County. He said the hardest hit area of Newburgh was just north of the city limits.
He described the scope of the damage as "very shocking."
"There was a whole apartment complex that lost all of the top floors of the units and then some of the second floors," Bennett told CNN. "I talked to people who were in the streets crying."
Bennett estimated the damage path was about three-fourths of a mile wide and 20 miles long.
Groupey said officials had declared a local state of emergency, the first step toward requesting state assistance.
Many residents said the storm moved through quickly, with the rush of wind lasting a matter of seconds.
One area resident, Joel Johnson, told WFIE: "You could hear the wind; it really does blow like a train."
The National Weather Service had issued warnings for the area about 30 minutes before the tornado struck, but many people were asleep and not aware of them.
Bennett said the county set off tornado warning sirens about 10 minutes before the storm slammed the area.
A spokeswoman for the American Red Cross said the agency was providing food, clothing, shelter and mental health assistance to about 35 families in the area.
Assistant Fire Chief Matt Timmel, from the volunteer fire department in Newburgh, said rescue efforts were taking place in "very rural country."
"They found one family deceased in the middle of a bean field," he said.
It was the deadliest day of tornado activity in the United States since April 8, 1998, when a twister killed 32 people in Oak Grove, Alabama, and five more in other parts of the state and in Georgia and Mississippi.
John Asher, vice president of communications for Churchill Downs, which owns Ellis Park horse track in Henderson County in Kentucky, said some of the 150 racehorses there died.