Chilean riot police used water cannon and tear gas for a second day running to scatter secondary school students protesting over education reform.
Most of the protesters are high school pupils
Officials and student leaders have been talking but the government has rejected a demand to respond by Friday or face a national school strike.
Mass demonstrations on Wednesday saw more than 700 people arrested.
President Michelle Bachelet condemned the police's handling of the unrest and sacked the head of special forces.
After several hours of talks on Wednesday, government officials and student leaders emerged to say no deal had been reached.
Demonstrators are demanding educational reforms including a new curriculum, free bus fares and no exam fees.
The students have threatened to resume school strikes next week unless the government agrees to provide more education funding.
"If there is no response from the education ministry and the authorities to our petitions, we will call on Monday for mobilisation at a national level," one student leader told a news conference.
But Education Minister Martin Zilic said the government was analysing the issues and would respond when "it had an answer."
Government spokesman Ricardo Lagos Weber said any ultimatum was counter-productive given that the government was already talking to students.
"The government is listening, talking and then will take decisions," he said.
The dispute is being seen as a big test for President Bachelet who took office in March.
Television footage and pictures splashed across newspapers of police beating young protesters provoked a barrage of criticism on Wednesday provoked a barrage of criticism from parents.
President Bachelet criticised the police for "unacceptable excesses" in their treatment of the demonstrators, most of whom are secondary school students, and sacked the head of special forces, Osvaldo Jara.
"We will not accept detestable acts like we saw (Tuesday)," she told a news conference.
She said her government would look at which of the students' demands were viable.
Protests began several weeks ago when students took over several schools in Santiago, and the strike has now spread nationwide with many pupils staying in school but refusing to attend lessons.
Tuesday's protests were the biggest student demonstrations in Chile in several decades.
Both police and students say the violence has been provoked by masked protesters throwing stones.