Syrian fighters and defectors launched an offensive on Tuesday to take over downtown Aleppo, battling Syrian army and intelligence personnel at the gates of the Old City, a United Nations World Heritage site, residents and opposition activists said. In the northern outskirts of Aleppo, Syria's main commercial and industrial hub, President Bashar Al-Assad's forces put down an overnight mutiny at the city's prison, killing 15 prisoners with tear gas and machineguns, activists in contact with surviving prisoners said, according to a report of Reuters.