Damage assessment team from the National Weather Service traveled Monday to Wapello, Mahaska and Keokuk Counties.
They are determining whether storm damage Sunday afternoon was caused by tornadic activity or straight line winds.
A woman was killed in Keokuk county and another person was critically injured during the storms.
Emergency management coordinator Larry Smith says the damage in Keokuk County was in rural areas stretching fromt he southwest to the northeast corner of the county.
In Mahaska Countym the roof was torn off a medical building in Oskaloosa.
A number of homes were damaged in Ottumwa.