The Federal Emergency Management Agency has 600 workers assessing damage in the Oklahoma City area battered by tornadoes and violent storms.
Gov. Mary Fallin says crews are searching flooded areas for missing people and the death toll could rise.
Ten people are confirmed to have been killed in Oklahoma as a result of Friday's storms. Five others were killed by flash flooding in Arkansas and Missouri.
More than 75 other people were hurt, five critically.
The Oklahoma Highway Patrol says a mother and child were killed as tornadoes moved through Oklahoma City.
Highway Patrol Trooper Betsy Randolph says troopers found the bodies near a vehicle along Interstate 40 west of the city Friday.
Oklahoma Department of Transportation crews are working closely with the Oklahoma Highway Patrol to close interstates and highways metro-wide as necessary. All travel is strongly discouraged as emergency crews continue to respond to tornado damage and flooding.
Tens of thousands of OG&E customers are without power, according to the utility's System Watch.