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.
A spokeswoman for the city of Oklahoma City says there is widespread flooding across the city following a violent storm that produced a tornado.
Kristy Yager says city street Superintendent Randy Moulder is waiting for the rain to end before sending crews out in an effort to deal with the flooding. Yager says about an inch of water was also standing on the first floor of City Hall.
The National Weather Service issued a rare tornado emergency Friday during the early evening hours for the Oklahoma City metropolitan area. The weather service issues an emergency if a storm with tornadoes is heading toward large metropolitan area.
The warning covered Will Rogers World Airport in Oklahoma City. The airport's website says passengers were moved to underground tunnels and no flights are arriving or departing.
Oklahoma City area hospitals are reporting critically injured patients after a deadly tornado that killed at least two people struck the metro area.
Integris Health System spokeswoman Brooke Cayot says three of the system's hospitals received close to 50 patients and that five are in critical condition and one of those critically injured is a child.
Mercy spokeswoman Rachel Wright says the hospital took in four patients — all in stable condition.
Two of those critically injured were in vehicles that were on Interstate 40 west of Oklahoma City when they were caught in the tornado.
The warning coordination meteorologist at the National Weather Service in Norman says a storm that spawned a deadly tornado in Oklahoma had virtually everything.
Rick Smith says Friday's storm brought tornadoes, hail, lightning, heavy rain and people backing up highways with their cars. He calls it "one of the craziest storms" he's worked.
Smith says he doesn't think damage from the storm will approach the damage from a May 20 tornado that struck Moore. He says Friday's storm stayed primarily in a rural area west of Oklahoma City and dissipated just as it approached the heavily populated city.