Complex sentence: Two days before the Plainfield riots began, the Newark rioting had broken out (a riot that was still going on as of July 14,1967), and many communities in northern New Jersey were on edge, Plainfield included.
Split into simpler sentences: Two days before the Plainfield riots began, the Newark rioting had broken out It continued as of July 14,1967. Many communities in northern New Jersey were on edge, Plainfield included.