BBC with :56 violence video
Police arrested at least 280 people...with 45 reported injured...during a march that turned violent commemorating the 38th anniversary of a coup against President Salvador Allende in 1973.
A teenager is in critical condition with a bullet in his chest.
The march in Santiago is held to remember the more than 40,000 people who were killed, disappeared, or tortured and jailed during the military dictatorship.