The town suffered a "direct hit" from the tornado and parts of the city have been devastated, local media says.

Power lines and phone lines in the city are down, reports say.

Missouri Governor Jay Nixon has declared a state of emergency and warned more storms are on the way.

He said storms had caused extensive damage across Missouri. He warned that the storms were not finished.

"I urge Missourians to keep a close eye on the latest weather information and to follow the instructions and warnings of emergency personnel as these deadly storms continue to move through our state," said Governor Nixon.

The Red Cross has opened a shelter at Missouri Southern State University in Joplin for victims of the disaster. It has also sent an emergency response vehicle with some supplies such as blankets, cots, water and food to the area.

US President Barack Obama - on his way to the Republic of Ireland - sent his condolences to those affected.

Last month, tornadoes and storms killed at least 350 people in Alabama and six other southern states.