A heavy firefight broke out on Monday between Free Syrian Army rebels and forces loyal to President Bashar Assad in a main district of the Syrian capital Damascus that is home to several security installations, witnesses said.They said the sound of heavy machinegun fire and rocket-propelled grenades (RPGs) echoed through the heavily guarded al-Mezze district. There was no immediate word on casualties but residents said by telephone the fighting was intense."There is fighting near Hamada supermarket and the sound of explosions there and elsewhere in the neighborhood. Security police have blocked several side streets and the street lighting has been cut off," a housewife who lives in the area said. The fighting in the capital came after a car bomb ripped through a residential area of Syria's second city Aleppo on Sunday, and as activists reported heavy clashes across the country between state forces and rebels fighting to overthrow Assad. As hundreds gathered on Sunday in...