A tornado damaged airplane is pictured at Canadian Valley Technology Center's Aviation Technology building in El Reno, Oklahoma June 1, 2013. [Photo/Agencies]

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.

Cloud to ground lightning strikes near storm chasers during a tornadic thunderstorm in Cushing May 31, 2013. [Photo/Agencies]

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.