The twisters are part of a severe weather outbreak that is sweeping through the region as storms move east . NEW : A tornado strikes Illinois the weekend , a county official says . `` We do n't know for sure that it 's over yet , '' says an official . Tornadoes tear through Illinois , Kansas , Oklahoma and Illinois . One person is killed in Pottawatomie County , Oklahoma .
NEW : A tornado strikes Illinois the weekend , a county official says . `` We do n't know for sure that it 's over yet , '' says an official . Tornadoes tear through Illinois , Kansas , Oklahoma and Illinois . One person is killed in Pottawatomie County , Oklahoma .