Clashes erupted tonight between protesters and Central Security Forces in Cairo's Tahrir Square. The fighting began after 15 people from a group of families of people killed in Egypt's 25 January revolution were arrested, witnesses told Al-Masry Al-Youm. The protesters then attempted to march to the Ministry of the Interior, nearby Tahrir Square, when 20 more people were arrested, witnesses said. Central Security Forces (CSF) fired multiple rounds of tear gas at protesters, while protesters threw rocks at the CSF. The clashes occurred on Qasr el-Ainy Street, a main Cairo thoroughfare, and Mohamed Mahmoud Street, which borders the American University in Cairo's downtown campus. At least 10 civilians have been injured in the clashes so far. Protesters chanted, “The people want the downfall of the general,” in reference to General Mohamed Hussein Tantawi, the head of the ruling Supreme Council of Armed Forces. Tahrir Square was the epicenter of Egypt's 18-day uprising that toppled former President Hosni Mubarak. The last clashes between protesters and the state in the suqare occurred on 9 April when military forces stormed the square, firing hundreds of gunshots and injuring several protesters.