A female suicide bomber struck black-clad worshippers preparing for Shiite Islam's holiest day, killing at least nine in an attack that highlighted insurgents' widening array of tactics against a US-led offensive in key areas on Baghdad's doorstep. A witness said people shouted slogans against al-Qaida in Iraq as they carried the dead and wounded from Wednesday's blast scene near a marketplace in Diyala province - a region of farmland and palm groves northeast of Baghdad that holds strategic havens for extremists. Diyala remains one of Iraq's most violent regions and is a main battleground for US and Iraqi troops trying to overwhelm al-Qaida strongholds in the capital and elsewhere around the country. Many extremists fled for safer ground before the new offensive began last week, reducing the expected threats from roadside bombs and ambush attacks. But insurgents left behind a more unconventional - but still deadly - landscape of booby traps and tripwire explosives.