The streets of the Iranian capital Tehran are quiet once more after a fourth night of violence in which pro-democracy demonstrators clashed with hardline supporters of the country's clerical leadership.
The protesters had been warned to expect no pity
Security forces and hundreds of vigilante militia used tear gas, clubs, chains and iron bars to disperse the protesters.
The BBC's Miranda Eeles in Tehran says militants from groups such as Bisji and Hezbollah were harsh in their methods - she saw one protester carried off on a motorbike wedged between two vigilantes, with a chain tight around his neck.
But despite the tough treatment, and warnings from Iran's supreme leader Ayatollah Khamenei that demonstrators would be shown no pity, our correspondent says the demonstrators' resolve to continue speaking out against the slow process of reform shows no sign of waning.
"Given the warnings I was expecting the number of protesters to be fewer, but I was completely wrong - the demonstrators were really out in force last night," she said.
In an effort to thwart the crowds, police had completely sealed off the area around Tehran University - the centre of the protests, which were sparked by plans to privatise the university.
However, nearby streets were jammed with cars sounding their horns, filled with ordinary Iranians who had turned out to express their support for the students.
Stones were thrown and chants wishing death on Ayatollah Khamenei were heard.
Such condemnation of the supreme leader is said by experts to be unprecedented in Iran.
Our correspondent says there were even calls for the reformist President Mohammad Khatami to resign.
"They feel totally let down by President Khatami - they voted him in six years ago on this platform of reform and they just haven't seen any changes," she says.
The streets are now reported to be quiet, with no sign either of the protesters or the armed militia, some of whom had been carrying assault rifles.
The authorities have accused the United States and Iranian exiles of fomenting the unrest.
Exiled opposition groups have been encouraging the protests through US-based satellite channels.
One senior cleric, former President Akbar Hashemi Rafsanjani, said at Friday prayers that the US was trying to "snare" Iran's young people.
The authorities are anxious for the situation not to get out of hand.
They have stressed to students that they will not tolerate a repeat of the events of 1999, when clashes with law-enforcement officers lasted for three days and left at least one student dead.
Those anti-government protests were the most serious since the fall of the Shah in 1979.
Have you been involved in the protests? Have they affected you in any way? Tell us your experiences
Disclaimer: The BBC may edit your comments and cannot guarantee that all e-mails will be published.