Dark smoke rose from the US-protected Green Zone early Sunday after it was targeted by a series of rockets or mortars. Some 10 blasts were heard in the sprawling area in central Baghdad starting shortly before 6 a.m., and helicopters buzzed overhead. The US public address system there warned people to "duck and cover" and to stay away from windows. There were no immediate reports of casualties. "Our assessment at this time is that the attack caused no deaths or major casualties," said Mirembe Nantongo, spokesman for the US Embassy in Baghdad.