A shelling of the US-protected Green Zone caused no casualties and did no damage, a US military spokesman said late Saturday. Starting about 6:15 a.m. Saturday, nearly 10 blasts could be heard in the sprawling area along the Tigris River that houses the US and British embassies, the Iraqi government headquarters and thousands of American troops. Col. Steven Boylan, a spokesman for the top American commander in Iraq, Gen. David Petraeus, confirmed the Green Zone was hit by indirect fire - its term for a rocket or mortar attack - but said there were no injuries or damage. The explosions came just a day after powerful Shiite cleric Muqtada al-Sadr ordered his Mahdi Army militia to extend its cease-fire by another six months. It was the fourth time this week that US outposts in Baghdad appeared to be the targets of rocket or mortar attacks. Brig. Gen. Mike Milano, who oversees security in Baghdad, said at a news conference earlier in the day, that those attacks killed "31 men, women and children."