Dozens of Chilean students interrupted a meeting at the Senate headquarters in Santiago to press their call for a referendum on Chile`s social problems, according to BBC.
The students broke in as lawmakers and the education minister were discussing next year`s budget.
The protesters left several hours later after opposition lawmakers promised to introduce a bill calling for a referendum.
Students have been protesting for months to demand free public education.
The Senate`s education committee had gathered to discuss the budget when dozens of young people, many of them high school students, burst into the room.
Three youths climbed on top of the committee table and unfurled a sign which read "Plebiscite now".
Some of the students, who were streaming their actions live on Twitter, then occupied the building for several hours.
Outside, police sealed off the entrance to the building with metal barriers to keep more protesters from entering.
They confronted a crowd of hundreds of students and parents outside who were carrying signs demanding "Free Education" and "Referendum Now".
Education Minister Felipe Bulnes and others taking part in the Senate committee meeting hurriedly left the building.
Protesters shouted and threw coins at Mr Bulnes.
The Senate president, Guido Girardi, who is a member of the opposition Party for Democracy, spoke to the protesters and promised they would not be dislodged by force by the police.
He has been critical of the government`s handling of the students` protests.
The students have been boycotting classes and staging demonstrations for almost six months.
On Tuesday, police in Santiago used tear gas and water cannon in clashes with masked protesters who set up burning barricades and threw petrol bombs; 260 people were arrested.
The government said after these violent demonstrations that it would invoke an emergency security law to help quell student unrest - the most serious in Chile since 1990.
On Wednesday, students held another mass demonstration to press their demands.
Talks over education reform broke down this month and there is no sign of a resolution.
Indeed, positions appear to be hardening.
Student leaders are demanding wholesale reform of Chile`s education system, which they say is unequal and under-funded, but they have condemned the violence.
They want the central government to take full control of education and increase spending on public schools and universities.
President Sebastian Pinera has responded by promising limited reforms and around $4bn (£2.6bn) in extra funding.
On Tuesday, he approved a law increasing subsidies for children from poor backgrounds attending private schools.
But he has categorically rejected calls for full state control and free education.