Iranian opposition protesters clash with security forces in Tehran during the Shiite mourning event of Ashura. Photograph: AFP/Getty Images

  It was meant to be an event when Iranians unite to honour one of Shia Islam‘s most revered martyrs. Instead, it turned into a day of bloody carnage that left at least nine dead, many more injured and the country facing a potentially unbridgeable divide and an escalating cycle of violence. The Shia mourning ceremony of Ashura became the setting for all-out confrontation between Iran‘s torn political factions when the government unleashed a furious crackdown on pro-opposition protesters that included orders to open fire. In the most violent clashes since the aftermath of last June’s disputed presidential election, security forces fired on demonstrators who had gathered in their thousands in some of Tehran’s main thoroughfares. Riot police and plainclothed agents attacked people with batons and iron rods, aiming for the head to exact maximum damage, said witnesses. Ali Mousavi Khamane, a nephew of the reformist opposition leader, Mir Hossein Mousavi, was killed after being shot through the heart in the city’s Enghelab Square. The 35-year-old’s death could provide the opposition with a fresh rallying point by turning him into a martyr in its struggle against the regime. Earlier, an elderly man had been killed after being shot through the forehead at Valiasr crossroads. The crackdown was triggered by the opposition Green Movement’s decision to use Ashura – which commemorates the death of Imam Hossein, the Prophet Muhammad’s grandson, at Karbala in 680 – as a day of protest. The movement has been forced to limit its demonstrations to state-sanctioned occasions in recent months in the face of a fierce government crackdown. Opposition backers yesterday turned out in their largest numbers since last June’s post-election protests, despite official warnings that the government would clamp down hard on dissent. Showing that it anticipated widespread violence, the government had cancelled all leave for emergency workers beforehand and put hospitals on alert to expect casualties. Witnesses reported seeing members of the special forces being ordered by their commanders to kneel and fire on the demonstrators. The reformist website, Rah-e Sabz, said some soldiers refused to obey orders. One was said to have been slapped by his commander and threatened with a military tribunal unless obeyed. Rather than be cowed, however, demonstrators responded furiously. Reports from bystanders and on opposition websites described protesters attacking the security forces with stones. Some members of the security forces were assaulted with their own batons after having them seized. Other had their uniforms ripped away as they tried to assault demonstrators in Laleh park, Tehran. In a sign of open rebellion, police cars and motorcycles were set ablaze, and some reports last night said government buildings were on fire. The fury of the protesters was directed more at Iran’s supreme leader, Ayatollah Ali Khamenei, rather than at the president, Mahmoud Ahmadinejad. Many chanted slogans including: “Khamenei is a murderer, his leadership is illegitimate.” Some of the chants linked Khamenei directly to rape allegations levelled by some opposition activists against the security forces after the election. The chants were one of the clearest sign yet of the rapid collapse of Khamenei’s moral authority. In Iran’s conservative culture, rape is often regarded as an equally heinous crime as murder. Turning the religious tables on the Islamic regime, opposition supporters have sought to compare Khamenei to the Umayyad caliph, Yazid, who was responsible for Imam Hossein’s death and is seen as a cruel tyrant in Shia Islam. Hossein Bastani, an Iranian analyst based in France, said the nature of the demonstrations had changed since the post-election period and that most protesters now wanted a change of regime. “Several months ago most people didn’t want regime change,” he said. “But now because of the behaviour of Khamenei and Ahmadinejad, most are now in favour of some kind of regime change. They think there is no possibility that this regime or government can be modified. The other thing that has changed is that people are no longer keeping their faces covered. They know that the consequences of being identified and caught can be very serious, but they no longer care.” The government last night dismissed reports that it had ordered forces to fire on demonstrators – a denial it also issued during the post-election upheaval, when, the opposition claims, at least 72 people were killed. “No report of death has been sent to the police,” Azizollah Rajabzadeh said, according to the semi-official ISNA news agency. “No one has been killed. Police did not open fire and the present officers did not carry weapons.” The White House condemned the “unjust suppression” of civilians. “Hope and history are on the side of those who peacefully seek their universal rights, and so is the United States,” said Mike Hammer, the White House national security council spokesman.

Voices from the street: Protesters’ stories

Mohammad, 25, economic student, who was at Kalaj bridge: “I witnessed three people being killed. The security forces were beating people like dogs. The forces were ordered to kneel and aim and shoot at people directly. We were Kolaj bridge and people started attacking. The security forces began shooting at people. I saw one of them, his brain was blown out. People started chanting: ‘I kill, I kill, the one who killed my brother.’ People for the first time are defending themselves by throwing stones and also with batons. People have been attacking them bare-handed. The plain-clothed agents are grasping pieces of metal sticks and beating people on the head.” Ali Reza, 23, computer engineering student at Tehran Azad University, who was at Ferdowsi Square: “In Azadi Street close to Eskandari Street people are attacking the forces. Most of the slogans have been against Khamenei rather than Ahmadineiad. In Imam Hossein Square, people set fire to the forces’ motorcycles and ripped off the clothes of the revolutionary guard. One basiji, who was carrying a dagger in Azadi Street, was severely injured when people attacked him. In Laleh Park, 50,000 people had gathered. Around 50 or 60 of the security forces were ‘arrested’ by people and had their clothes ripped off. The forces are aiming at the upper part of people’s bodies.”