File photo of police guarding the entrance to the St. Louis County Justice Building in Clayton


1 OF 3. Police guard the entrance to the St. Louis County Justice Building in Clayton, Missouri as protestors gather in the street in this August 20, 2014 file photo. CREDIT: REUTERS/MARK KAUZLARICH/FILES

Police guard the entrance to the St. Louis County Justice Building in Clayton, Missouri as protestors gather in the street in this August 20, 2014 file photo. REUTERS/Mark Kauzlarich/Files