A Delhi police head constable and a home guard were brutally beaten up by a group of unidentified car-borne assailants in Pandav Nagar on Thursday. Head constable Dalchand (49) stopped a biker to check his documents. Soon a heated argument ensued between them. The biker then left and returned with friends who beat him and and home guard Sahib Singh (40), who tried to intervene and stop the assailants.