Oklahoma, Jun 1 (Reuters) : Deadly tornadoes slammed Oklahoma City and wreaked havoc killing five people, including a mother and her baby, days after the region was battered by a monster storm that claimed 24 lives.

According to the Oklahoma Highway Patrol Trooper Betsy Randolph, the woman and her child were killed when their SUV overturned on the state highway as an enormous tornado swept through the area yesterday.

The mother and her baby were among five people killed as a result of severe weather, and another 14 were injured, authorities said.

"We try to tell people not to drive into the storm," Oklahoma Highway Patrol Trooper Betsy Randolph said.

"And this may have been one of those deals where there was little or no notice or warning. It's just so gut-wrenching and it's so heartbreaking," she said.

The accident happened as an enormous tornado swept through the area yesterday. The tornado was part of a midwestern storm system that spun off twisters as far away as St Louis, Missouri.

More than 50,000 people were without power by yesterday evening in the Oklahoma City area because of the severe weather, the Oklahoma Gas and Electric Company said.

Also, more than half the city of Mustang, 27 kilometres south of Oklahoma City, was without power, Mustang Fire Chief Roy Widmann said.

The National Weather Service has warned a "confirmed and extremely dangerous tornado" was near the city of Harvester, about 40 kilometres northwest of St Louis.

The tornado was moving east at 80 kmph, said Colene McEntee, the St Charles County Emergency Management coordinator.

Authorities in Missouri urged people to take shelter as tornado emergency was announced for Oklahoma City as well as for its suburbs of Moore, Yukon and Bethany.

High winds were forecast for Moore, the suburb where a monster tornado had killed 24 people, including 10 children on May 20.

Oklahoma City's Will Rogers World Airport was evacuated over the threat from the approaching tornado, and travellers were sheltered in the airport's basement at the height of the storm, authorities said.

"They are now in the process of slowly allowing people out of their shelter. They are bringing employees up now, and then the passengers will be able to come up once the terminal is properly staffed," said Karen Carney, a spokeswoman for the airport.

"Right now, the airport has no power. Without power, they probably will not be able to allow passengers into the secure areas of the airport. But they obviously can't allow any takeoffs and landings without power, either," Carney said.

Even those people in the National Weather Center a building on the University of Oklahoma campus with tenants that include the National Severe Storms Laboratory and NOAA's Storm Prediction Center, "have been urged to stay away from windows due to potential for 80-90 mph winds," according to a tweet from weather service's Norman office, which also is based in the building.

Police and firefighters were responding to reports of damage in El Reno, just outside Union City, but it was not immediately known how bad the damage was, Mayor Matt White said.

Authorities were urging people in the path of the tornado to take immediate cover, and Oklahoma Governor Mary Fallin was urging residents not to take any risks.