Indonesian police used water cannon against protesters who broke into the grounds of parliament demanding that legislators approve key constitutional reforms.
Police sprayed the students after several protesters began rocking and climbing the heavy steel gates at the main entrance.
The cheering demonstrators toppled the gates despite their drenching but were halted by rolls of barbed wire, which were guarded by dozens of riot police and six water cannon.
The students later rolled the wheeled gates onto the main street, to the cheers of fellow demonstrators who totalled around 2,500-3,000.
Representatives of all parliamentary factions met the protesters after the incident. They signed a pledge prepared by the demonstrators to push for the constitutional amendments.
The People's Consultative Assembly, the top constitutional body, is discussing amendments to introduce direct presidential elections and make the assembly a fully elected body. Its annual 10-day meeting at parliament ends Saturday.
The students waved banners reading "Anti-amendments equal to anti-reforms" and "Amendment is needed for a clean and legitimate government". Supporters of the changes say they are crucial for bolstering democracy after decades of authoritarian rule under founding president Sukarno and his successor Suharto.
A compliant rubber-stamp assembly, which then had large numbers of unelected members, kept Suharto in power for decades by routinely re-electing him.
The rally was necessary because "the 1945 constitution was hastily made and has a lot of flaws because it was initially intended to be used as a provisional constitution", one protester, who gave his name only as Andi, told AFP.
The president and vice president are currently elected by the assembly – which is now composed of the 500 members of parliament plus 200 representatives from the regions and major mass organisations.
Also on the agenda of the current meeting is a controversial proposal to require Muslims to follow Sharia Islamic law. Thousands rallied in the capital on Saturday and Monday to support the proposal, which is unlikely to be adopted.