The violence began early on October 18 as protesters set up burning barricades on several main avenues across the capital, blocking rush hour traffic. Masked assailants set fire to a city bus, and police raided university buildings in pursuit of suspects.

Police used tear gas and water cannon against masked protesters who threw petrol bombs.

With more demonstrations planned for October 19, the government has said it will invoke an emergency security law to help quell the violence.

Interior minister Rodrigo Hintzpeter said those responsible for the bus attack would be prosecuted under the rarely-used Law of State Security, which allows tougher sentences for violent offenders.

BBC