Rescue teams have been mobilised and a full-scale operation is underway.
"We have had a massive tornado, a huge one has passed through this community. We do know there are fatalities, we don't have a number count yet, we know there are a lot of injuries," said Mary Fallin, Oklahoma State Governor.
"We know we have lost a tremendous amount of structures throughout this community and throughout the state," she continued.
It is feared many are trapped in collapsed buildings. At the Plaza Towers Elementary School, children have been pulled from the debris.
"I just wanted to say first of all that our prayers and our thoughts are with the Oklahoma families that have been hit hard by this terrible storm these last two days," added Fallin.
"In particular our hearts are just broken for the parents that are wondering about the state of their children that have been in the schools that have been hit today."
Source: Euronews