(Reuters) - Dozens of people were rescued from rising floodwaters and felled trees that smashed homes and blocked roadways in Oklahoma, as severe storms unleashing tornadoes and heavy rain roared through the central United States on Tuesday.

Rescue crews using boats pulled at least 50 people from rising water as heavy downpours inundated roads and homes, Oklahoma Emergency Management Agency spokeswoman Keli Cain said, although there were no reports of deaths or serious injuries.

Only the tops of cars engulfed by water were could be seen in video footage of roadways near Oklahoma City, and some houses were entirely surrounded by floods.

“It’s real dangerous,” said Ross Reuter, a spokesman for Canadian County, where 10 people were rescued. “Motorists get out into the swift water, thinking they can get across and it ends up being deeper than they think.”

Parts of the state have received six to eight inches (15-20 cm) of rain since Monday, and some 4 million people remained under a flash flood warning or watch in the region, the National Weather Service said.

A tornado that touched down early on Tuesday near Tulsa International Airport was among more than two dozen that have ripped through the region since Monday, according to the weather service.

“We have lots of reports of damage coming in. There is a lot of tree damage. Very large trees have been uprooted that are blocking roads and that have landed on houses,” NWS meterologist Sarah Corfidi said.

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Missouri Governor Mike Parson declared a state of emergency, citing flash flooding, “straight-line winds,” heavy rain and hail.

“Missouri is experiencing a very dangerous severe storm system with multiple threats that must be taken seriously,” Parson said in a written advisory. “I urge all Missourians to closely follow their local weather forecasts, take storm warnings seriously, and quickly act to protect themselves and their families when necessary.”

Some 22 million people are in the path of the severe weather system that was expected to move across Texas and Louisiana into Alabama and as far north as Iowa and Nebraska on Tuesday. A second storm system was brewing and could hit the same southern region of the country later this week.

“The whole area is in the bull’s eye, with more rounds of severe storms possible,” Corfidi said.