Forecasters say a tornado that hit near Owasso on Thursday had a preliminary ranking of EF1 with wind speeds of 90 mph to 100 mph.
The National Weather Service in Tulsa says more surveys are underway to determine whether any other twisters struck the state a day earlier.
Trees were downed and some homes sustained roof damage in Owasso, where the EF1 tornado hit. Storm spotters also reported tornadoes in Perkins and Ramona in Oklahoma and near Oologah..
The storms are moving out of Oklahoma but some areas could see flooding because of the heavy rainfall. The Storm Prediction Center in Norman, Oklahoma, says the greatest risk Friday for severe storms is in Gulf Coast states.