Severe weather in Oklahoma has left four people dead, including a 12-year-old boy and his mother, officials say.

The National Weather Service has warned of a large storm system bringing heavy rain and a threat of tornadoes to the Ohio and Tennessee valleys.

Two people were killed after two vehicles were swept off the road due to flooding caused by heavy rainfall in Moore, Oklahoma, police said. Following a search, the bodies of two people, an adult female and a 12-year-old child,