berlin german police investigate four people suspect plan islamist-motivated attack raid nine locations berlin eastern state saxony anhalt thursday prosecutors say four suspect age 18 21 accuse members islamic state group prosecutors police say statement three believe syria two travel berlin via istanbul islamic state-held territory syria november 2016 third accuse receive military train syria fourth believe help three travel prosecutors say arrest make raid mount 130 officer include special force confiscate electronic devices general prosecutor office berlin investigate four suspect age 18 21 suspect membership terrorist organization well prepare serious crime state statement say bild newspaper say police arrest number people suspect link fail asylum seeker kill 12 people drive truck crowd berlin christmas market last year tunisian anis amri escape launch dec. 19 attack shoot italian police milan less week late affair expose fail intelligence agencies stop surveillance amri conclude pose danger security christmas market beef year guard concrete block german police raid locations link islamist militants