Protestors ripped the doors off a police car, as they pushed it towards the line of black-clad Central Security Forces (CSF) officers guarding the road leading to the American Embassy. From 100 meters away, they advanced, throwing rocks, until the crowd was perhaps a dozen meters away from the CSF line. Protestors set the car on fire next to the Omar Makram mosque, and black smoke billowed into the air, obscuring part of the CSF lines from view. Tear gas canisters volleyed through the black smoke, and protestors were driven back. The exchange was just one episode in ongoing clashes which started late last night and have continued unabated, as protestors angry at a film which insults the prophet Mohamed seek to make their way to the American Embassy, which is less than 250m from Tahrir Square. Early in the afternoon, at most points 30 to 40 people, mostly men aged from their mid teens to mid twenties, were directly taking part in the fighting. Petrol bombs were occasionally thrown by the protestors. Both sides threw rocks, and protestors picked up burning hot tear gas canisters, and lobbed them back towards security services. Protestors and CSF troops alternately chased each other up and down the road between the Omar Makram mosque and the Mugamma, a huge, brutalist government building which sits on the south side of Tahrir Square. A hundred protestors milled around those directly involved in the fighting, in the road by the Omar Makram mosque, close to the fighting, yet not actively involved. And further back still, hundreds more were standing in the south of the Square, venting their anger over the amateurish film, apparently made by anti-Islam activists, which depicts the Prophet Mohamed as a gay, wine-drinking fraud. Earlier in the day, reports on social media had identified most of those clashing with CSF as 'ultras', organised hardcore football fans, who have been a fixture in Cairo street battles since the beginning of last year. But by mid afternoon, the composition of the crowd was diverse. Egypt Independent found only one person identifying as an ultra, and saw few people wearing the beards and dress typical of Salafis, conservative, or orthodox Islamists. “I am here as an individual,” said Hussam, 27. “Perhaps there are some ultras here, but it's as individuals. We feel humiliated. We can't believe the CSF are protecting them while they do these things.” One 21 year old protestor said he was a member of 6 April, but present as an individual, not as a member of that organisation. Mahmoud Sayed, 69, who works for the Ministry of Heath, expressed what appeared to be a common demand amongst protestors. “The ambassador has to be expelled," he said. "All we want is that, we don't want to kill him like they did in Libya.” Islam, 19, a student, agreed with Sayed's demand. “Our government, which we elected, has to bring us our rights. If they don't do this, we have to do it ourselves. They want us to fight and die for it, apparently,” he said. Amongst protestors interviewed by Egypt Independent, there was a palpable sense of humiliation, whereby the film was felt to represent an infringement of their dignity. Many saw the film as just one amongst a litany of humiliations which muslims had suffered at the hands of Western governments. As the call to the Islamic dhuhr prayer issued from the mosque around 3:20, the crowd, as if spontaneously, lifted their arms to call for a moment of peace. For twenty seconds, no rocks flew. Then, the the clashes resumed. Around 4 pm, heavy tear gas pushed protestors back from the Omar Makram Mosque, all the way to Mohammed Mahmoud Street. White tear gas vapour steamed from cannisters on the square.