Suicide bombings of two Shiite mosques in Baghdad killed at least 17 people on Friday as thousands of Iraq's newly empowered majority sect marked Ashoura, the main event in their religious calendar. Separately, a rocket landed near a police station and close to a mosque in a Shiite district of northwestern Baghdad, killing three people and wounding five in a shop, police said. Hours later a suicide bomber killed two policemen and a member of the Iraqi National Guard in Baghdad, a police official said.In the first suicide attack, a man wearing an explosives- packed vest merged into a crowd near a mosque in the Doura area of southwestern Baghdad and blew himself up, survivors said. The blast killed 15 people and wounded 33, Yarmouk hospital said. Soon afterwards, an explosion shook a second Shiite mosque in western Baghdad, the U.S. military and police sources said. Police said two suicide bombers had approached a crowd outside the mosque. They were spotted by police, who shot them, but one still blew himself up, killing at least two people. Iraq's national security adviser, Mowaffaq al-Rubaie, told CNN he believed Abu Musab al-Zarqawi, a Jordanian militant who is Al-Qaeda's leader in Iraq, was behind the attacks.