Many of the injured suffered burns in fires caused by collisions , officer says . Three killed ; 14 other people hurt , five seriously . Comment: Officials ask motorists to avoid stretch of highway .
Many of the injured suffered burns in fires caused by collisions , officer says . Three killed ; 14 other people hurt , five seriously . Dust storm caused at least 30 wrecks on I-10 south of Phoenix , authorities say . Officials ask motorists to avoid stretch of highway .