CAIRO: Angry Egyptian protesters in Moqattam on the outskirts of Cairo have attacked the headquarters of the Muslim Brotherhood, with smoke coming from the building, an eye witness told Bikyamasr.com late Thursday evening. It is unclear exactly who the protesters are, but the Brotherhood has confirmed the building is under siege. Police on the scene are firing tear gas at the protesters in an effort to push them away from the area. The Brotherhood has claimed the attackers “burned down” the building, but witnesses say this is not the case, only a fire was seen and smoke was coming from the building. It came after a defiant speech by President Mohamed Morsi, where he accused those who are continuing to protest against him to be criminals. The speech led to angry chants in Cairo's Tahrir Square, with calls for Morsi to leave power. Boisterous anti-Morsi chants were also heard near the presidential palace where a few thousand protesters had gathered, but were blocked from getting close to the palace by a Republican Guard blockade. On Wednesday, after angry Brotherhood supporters attacked a peaceful sit-in near the palace, massive violent clashes erupted, which resulted in at least five deaths and hundreds of injured. On Thursday, following Morsi's speech, activists began fearing that it could be a prelude to violent reprisals against anti-Morsi demonstrators in Tahrir and near the palace.