Anti-government student protesters in Iran say they have been badly injured in violent clashes during four days of unrest in the capital, Tehran

Hundreds of hard-line vigilantes wielding sticks and iron bars chased and beat demonstrators outside Tehran University Friday night. Gunshots also echoed in the area as Islamic militants sped around on motorbikes trying to silence protests against Iran's supreme leader, Ayatollah Ali Khamenei. On the campus, students report dozens of vigilantes stormed at least two dormitories, beating up some students in their beds and detaining several others. A student spokesman said more than 50 students were injured in the attacks and some two dozen have disappeared. Observers say Friday's protests were the most widespread and violent of four consecutive days of demonstrations against Iran's clerical rule. It was also the first time in recent days police stood by and allowed Islamic militants to take part in the tough clampdown. Diplomats in Tehran say the Iranian government wants to send a clear message that the protests have crossed their line of tolerance. Security forces fired machine guns into the air and used tear gas and batons to put down the opposition.