berlin german police tuesday detain six syrians suspect plan attack use weapons explosives behalf islamic state militant group prosecutors say police detain suspect age 20 28 raid cities kassel hanover essen leipzig general prosecutor office frankfurt say statement 500 police officer take part raid eight apartments search four suspect arrive germany december 2014 two arrive follow year six apply asylum prosecutor office say asylum applications approve prosecutors say six syrians suspect members foreign terrorist organization call islamic state add accuse also suspect plan attack public target germany use either weapons explosives second time month syrians arrest suspicion plan militant violence early month 19-year-old syrian man detain suspicion plan bomb attack arrest come one month first anniversary attack berlin fail tunisian asylum seeker kill 12 people plow truck christmas market concrete block instal around christmas market several central square capital year festive season open couple weeks germany detain six syrian suspect plan attack