Activists Document Street Battles in Cairo Video of Friday's clashes in Cairo posted on YouTube by Gigi Ibrahim, an activist blogger. As my colleague David D. Kirkpatrick reports from Cairo, protesters battled police officers in several Egyptian cities on Friday, two days after more than 70 soccer fans were killed following a security lapse at a stadium in Port Said. Amid reports that the police, firing tear gas, birdshot and live ammunition, killed at least four demonstrators, activist bloggers filed a series of vivid reports on the clashes as they unfolded, transmitting text updates, photographs and video from the streets to social media sites like Twitter and YouTube. One remarkable video clip, shot on Friday afternoon during a street battle on Mansour Street in Cairo near the Interior Ministry building, appeared to show police officers seizing a religious leader who had approached them to offer a truce, holding his white skullcap aloft to signal his peaceful intentions. That video, uploaded to YouTube by Mosireen, a collective of activist filmmakers, seemed to contradict a report on Egyptian state television that the authorities were trying to negotiate with the protesters. The Mosireen filmmakers also posted video of protesters chanting and fleeing clouds of tear gas during clashes the night before, and tearing down a makeshift wall the authorities had recently erected to block off a street near Tahrir Square. Later, an activist named Omar Kamel uploaded a video of protesters fighting through clouds of tear gas on Friday night. At one stage on Friday, as the tear gas rained down on protesters, the activist blogger Hossam el-Hamalawy reported that an errant shell had struck a government building and started a fire. Minutes later, Mr. Hamalawy transmitted a photograph from his phone showing protesters scaling the outside wall of the building to reach the blaze and extinguish it. Mr. Hamalawy, who has carefully documented the role of soccer fans in Egypt's revolution on his Arabawy blog, also posted a somewhat surreal image on Flickr, of a man who stepped into the heart of the clashes to sell the flags of Cairo's two leading soccer clubs to protesters. While activists calling for an end to military rule in Egypt have embraced the diehard soccer fans known as ultras as allies in their struggle, an American journalist living in Cairo, Evan Hill, observed on Friday that the supporters of the Cairo club who were the main victims of this week's violence, the Ahly ultras, have a history of recreational violence that could well have played a role in Wednesday's riot. As Mr. Hill noted, a video posted on a YouTube channel that celebrates the exploits of the Ahly ultras showed them rampaging through Port Said when they visited the city last year. While not overlooking the failure of the police in the stadium to restrain the fans of Port Said's Al Masry team, who instigated the attacks on the Ahly ultras that led to so many deaths, Mr. Hill dismissed the idea that Wednesday's violence must have been sparked by provocateurs, pointing to the video as evidence that soccer fans are capable of filling a security vacuum with "ultraviolence."