Rockets or mortars have been heard being fired in the direction of the Green Zone in the Iraqi capital. There was no immediate word on casualties or damage. Black smoke could be seen rising after a blast from the heavily fortified area. Loudspeakers warned residents to take cover and await further instructions. The shelling Wednesday was the latest in a series of attacks on the part of Baghdad that houses the Iraqi government and US Embassy. Two US soldiers died in a similar attack last week.