Gunshots were heard in the early hours of Monday morning near a Tehran university dormitory that has been the focal point of six nights of pro-democracy protests, a witness said.
Hardline Islamic vigilantes, some carrying Kalashnikov assault rifles and wearing bullet-proof vests, patrolled the streets near the campus, which were clogged with thousands of cars carrying people trying to take part in the protests.
"I heard three gunshots quite clearly," a correspondent at the scene said.
"Immediately after the gunshots some of these hardliners jumped on their motorbikes and headed in the direction of the (sound of the) shots."
The protesters have vented most of their anger at conservative clerics who control the key elements of power in Iran.
But they have also lambasted the reformist government of moderate President Mohammad Khatami and his allies who control parliament, accusing them of failing to deliver change after six years in office.
US President George W Bush has praised the demonstrators, saying on Sunday their protests were a positive step towards freedom.
Iran has accused the United States, its arch-foe, of interfering in its affairs and exaggerating the demonstrations' importance.
nzoom link
Sounds like an excellent way for the freedom fighters to set up an ambush.