Polling stations opened around Iraq Thursday to allow Iraqis to vote for a new parliament. A large explosion was head in downtown Baghdad within minutes of the polls opening and sirens could be heard inside the heavily fortified Green Zone where the Iraqi government and the US and British embassies are located. Police said the explosion was reportedly caused by a mortar landing near the Green Zone. There were no immediate reports of any injuries or damage. In northern Mosul, where all polling stations opened, a bomb killed a hospital guard when it went off between a polling station and a hospital, initial US military reports said. A mortar also landed near a polling station without causing any injuries, the reports said.