The death toll from tornadoes that ripped through Oklahoma and neighbouring states this weekend has jumped to 12, authorities said, less than two weeks after a monster twister hit the area.

The Oklahoma Medical Examiner's Office announced nine fatalities, while authorities in Missouri said three people died as a result of flooding there in the aftermath of the storms. The Oklahoma Highway patrol says a mother and her baby were killed while travelling on Interstate 40, just west of Oklahoma City, when their car was picked up by the storm and they were sucked out of it.The latest storms dumped up to 20 centimetres 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.Photos showed streets looking like rivers, with stranded cars submerged in water as high as their door handles in some places.