Nowata County Undersheriff Doug Sonenberg tells KSWO-TV the infant and two adults were killed Friday when heavy winds destroyed a mobile home. They were found in a creek.
The Oklahoma Highway Patrol also reported that Ash Grove, Mo., resident Jimmy King was killed when straight-line winds flipped the semi he was driving onto a cement barrier wall and trapped him inside near Afton.
Troopers say the 70-year-old King was pinned in the wreckage for nearly three hours and died at the scene of massive injuries.
The storms were part of a system that unleashed winds of 25 mph to 35 mph as it moved through the state.
Information from: KSWO-TV