▁Mobile ▁Anti - Dist urb ance ▁Squadron ▁( , ▁ES MA D ), ▁police ▁pat rol men ▁John ▁Ar ce ▁was ▁killed ▁by ▁an ▁explos ive . ▁ ▁This ▁incident ▁was ▁followed ▁by ▁the ▁inc urs ion ▁of ▁the ▁police ▁force ▁into ▁the ▁university , ▁which ▁left ▁equipment , ▁buildings , ▁and ▁vehicles ▁dam aged . ▁ ▁On ▁September ▁ 2 2 , ▁ 2 0 0 5 , ▁during ▁a ▁protest ▁against ▁the ▁Free ▁Trade ▁Ag re ement ▁between ▁the ▁United ▁States ▁and ▁Colombia , ▁the ▁chem istry ▁student ▁J hon ny ▁Silva ▁Ar ang uren ▁was ▁killed , ▁according ▁to ▁some ▁witness es , ▁by ▁the ▁police ▁force . ▁ ▁While ▁most ▁of ▁the ▁university ▁community ▁is ▁against ▁the ▁actions ▁of ▁the ▁radical ▁movements , ▁this ▁has ▁not ▁prevent ed ▁the ▁st ig mat ization ▁of ▁the ▁student ▁body ▁by ▁the ▁general ▁population . ▁This ▁attitude ▁has ▁led ▁to ▁the ▁belief ▁that ▁the ▁gu err illa ▁and ▁sub vers ive ▁groups ▁that ▁operate ▁in ▁Colombia ▁have ▁c land est ine ▁oper atives ▁inside ▁the ▁university , ▁a ▁belief ▁that ▁has ▁been ▁supported ▁by ▁the ▁discovery ▁of ▁un con vent ional ▁weapon ry ▁inside ▁the ▁university ▁grounds . ▁ ▁This ▁has ▁resulted ▁in ▁the ▁target ing ▁of ▁student ▁activ ists ▁by ▁criminal ▁and ▁par amil it ary ▁groups . ▁ ▁On ▁October ▁ 4 , ▁ 2 0 0 6 , ▁a ▁student ▁of ▁Technology ▁of ▁Pre h ospital ▁Att ention ▁and ▁representative ▁at ▁the ▁Academ ic ▁Council , ▁Julian ▁And rés