Oklahoma City: Nine people were killed in tornadoes that swept through central Oklahoma on Friday, part of a storm system that caused widespread flooding in Oklahoma City and its suburbs, the state's chief medical examiner said on Saturday.
The dead included two children and seven adults, said Amy Elliott, a spokeswoman for the medical examiner's office. The death toll earlier had been reported as five.
The tornadoes struck just 11 days after a twister ranked as EF5, the most powerful ranking, tore through the Oklahoma City suburb of Moore and killed 24 people.
The latest storms dumped up to 8 inches (20 cm) of rain on the Oklahoma City area, causing flash flooding that submerged parts of the sprawling metropolitan area that is home to more than 1.3 million people.
Nearly two dozen people were rescued from areas cut off by rising water, the National Weather Service said.
More than 70 people were treated for storm-related injuries, Oklahoma hospital officials said.
Severe storms also hit neighboring Missouri, where Governor Jay Nixon declared a state of emergency on Friday, and were forecast to move into Illinois on Saturday.
The devastation was caused by large, long-lasting thunderstorms known as supercells, which produce the strongest tornadoes, along with large hail.
Forecasters believe at least five tornadoes touched down in central Oklahoma, which survey teams were trying to verify, meteorologist Rick Smith said from the National Weather Service office in Norman, Oklahoma.
"Some of these tornadoes were wrapped in rain and they were difficult to see," Smith said.
The tornadoes hit during the Friday evening rush hour and many of those hurt or killed were on the roadways.
Among the dead were a woman and her baby who were traveling on Interstate 40, just west of Oklahoma City, when their vehicle was picked up by the storm and they were sucked out of it, said Betsy Randolph, spokeswoman for the Oklahoma Highway Patrol.
One tornado rampaged down the interstate, tipping over trucks and hurling hay bales, a witness said. Television images showed downed power lines, tossed cars and motorists stranded in flood water.
"For reasons that are not clear to me, more people took to the roads, more than we expected. Everyone acted differently in this storm, and as a result, it created an extremely dangerous situation," said Oklahoma City Mayor Mick Cornett.
"I think we are still a little shaken by what happened in Moore. We are still burying children and victims, so our emotions are still strong," he added.
Brandi Vanalphen, 30, was among the hundreds of drivers trapped on traffic-snarled roads as she attempted to flee the tornado system menacing the suburb of Norman.
"What got me scared was being stuck in traffic with sirens going off," she said. "I started seeing power flashes to the north, and I said 'screw this.' I started driving on the shoulder. People started driving over the grass."
Moore had limited damage from the latest storm, said a police dispatcher for the city.
Elsewhere, homes were destroyed, roofs were torn off and power lines were ripped down. Work crews were repairing washed-out patches of roadways and removing downed trees in order to allow aid workers to get through.
Storms also swept into neighboring Missouri, where violent winds flipped over semi-trailer trucks on Interstate 70 between St Louis and St Charles County to the west, said Brett Lord-Castillo, spokesman for the St Louis County Emergency Management Agency.
Hollywood Casino St Louis was evacuated when part of its roof was blown off, Lord-Castillo said. No deaths or serious injuries were reported in the greater St Louis area.
Power utilities Oklahoma Gas and Electric and Ameren said 200,000 customers were without power in Oklahoma, Missouri and Illinois.
On Thursday, storms in Oklahoma and Arkansas killed at least three people, including Scott County, Arkansas, Sheriff Cody Carpenter, whose body was recovered early on Friday, said a spokesman for the Arkansas Game and Fish Commission.
A game warden was still missing on Saturday after attempting a water rescue on Thursday in Scott County, which got more than 2.5 inches (6.3 cm) of rain in two hours.
A man also died in Tull, Arkansas, when a tree fell on his car, and a woman's body was found in flood waters in Scott County on Friday.