At least six people were killed and many were injured in a series of thunderstorm and tornados that struck Oklahoma and Kansas City, according to US weather officials.

The Oklahoma's Canadian County Sheriff said that a large tornado near El Reno, a city in Canadian County, destroyed residences and caused a gas leak at an energy plant west of Oklahoma City, media reports said.

About 1,200 people were packed in a shelter in Newcastle, a community near Oklahoma City, during the storm, said Oklahoma City Manager Nick Nazar.

Oklahoma Governor Mary Fallin said residents should take tornado warnings and reports very seriously.  This is an extremely dangerous and life-threatening situation, the National Weather Service warned during the storms. Tornado watches were in effect Tuesday evening in Texas, Missouri, Arkansas, Oklahoma and Kansas.

Twisters also brewed in Dallas and several northern Texas counties, said the National Weather Service, with at least one tornado reported on the ground.