The governor of Oklahoma has declared a state of emergency in 16 counties after tornadoes tore through parts of the Midwest.
This is video of a twister touching down in the town of Shawnee.
Authorities say a 79-year-old man was killed after a tornado ripped through a mobile home park.
A helicopter pilot describes the scene.
Authorities say more than a dozen people were hurt.
According to the National Weather Service, as many as 26 tornadoes were reported in Oklahoma, Kansas, Illinois and Iowa.