OKLAHOMA CITY (AP) — At least six tornadoes may have touched down in northern Oklahoma earlier this week. National Weather Service crews surveyed damage in Craig, Nowata and Osage counties, and assigned a preliminary damage rating of EF-1 to three storms and EF-2 for another. A tornado damaged trees and power poles Sunday near Fairfax in Osage County, and trees and barns were damaged near Childers on Monday and Nowata on Tuesday in Nowata County. One person was hurt when a tornado broke windows at a house and damaged other structures near Welch on Tuesday. Forecasters assigned that storm a preliminary damage rating of EF-2. The weather service received reports of possible tornadoes on Monday near Medford and Nash in Grant County and Jet in Alfalfa County. Homes, outbuildings and power lines were damaged.