Thousands of police were today brutally suppressing a pro-democracy rally in central Tehran.
In a flurry of postings on blogs and Twitter, demonstrators described people being heavily beaten and shot.
There were claims that a girl had been hit by a hail of bullets and that the feared Basij paramilitaries were preventing people from getting to safety.
One blog, Revolutionary Road, claimed that there were 10,000 policemen massed in Baharestan Square in the south-east of the city.
Correspondents said there were army helicopters flying over the area and that police had used tear gas to suppress the protest.
The square itself had been blocked off, shops closed and the local train station also shut.