Betty Matthews searches through the rubble of what was once her home after a tornado ripped through the Falcon Lake area of Piedmont, Oklahoma May 24, 2011. Several tornadoes touched down in Oklahoma on Tuesday afternoon, the largest one striking El Reno, west of Oklahoma City, and continuing to the northeast, the National Weather Service said. [Photo/Agencies]

EL RENO, Oklahoma - A line of violent thunderstorms roared across middle America on Tuesday, killing six people in two states, with several tornadoes touching down in Oklahoma and high winds pounding rural Kansas.

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The high-powered storms arrived as forecast, just two days after a massive tornado tore through the southwest Missouri town of Joplin and killed at least 122 people.

Several tornadoes struck Oklahoma City and its suburbs during rush hour, killing at least four people and injuring at least 60 others, including three children who were in critical condition, authorities said.

Cherokee Ballard, a spokeswoman for the state medical examiner, said four people died west of Oklahoma City in Canadian County, where a weather-monitoring site in El Reno recorded 151 mph (243 kph) winds. She did not have any immediate details about the deaths.

In Kansas, police said two people died when high winds threw a tree into their van around 6 pm near the small town of St John, about 100 miles (160 kilometers) west of Wichita. The highway was shut down because of storm damage.

More severe weather was expected after nightfall as the storms continued east.

"Unfortunately, this event will likely continue for some time," Oklahoma Gov Mary Fallin said. "I am asking all Oklahomans to stay aware of the weather and to take proper precautions to keep themselves out of harm's way."

The line of storms began about 3 pm in Oklahoma and followed tracks greater than 40 miles (65 kilometers) into the state's capital city before continuing on toward Tulsa. Oklahoma state offices and many businesses let workers leave hours earlier to get out of harm's way.

Storm clouds also spawned funnel clouds and at least one tornado around North Texas, but there were no immediate reports of damage or injuries.