Gunmen ambushed a bus carrying police recruits to a training centre north of the Iraqi capital on Thursday, killing nine people, police said.
No one immediately claimed responsibility for the attack, but Sunni Muslim insurgents have been redoubling their efforts to undermine Iraq's Shi'ite-led government and foment inter-communal conflict this year.
Eleven unarmed Iraqi recruits were heading from the northern city of Mosul to a training course when gunmen driving two cars blocked the way and opened fire on their mini-bus in a village just outside Taji, 20 km (12 miles) from Baghdad.
"The shooting at their car was intense... eight of them were killed immediately, plus the driver, and another two were wounded and their wounds are critical," said Captain Muqdam Ali.
Iraq's power-sharing government has been all but paralysed since U.S. troops left more than a year ago and Prime Minister Nuri al-Maliki, a Shi'ite, is facing protests in the country's Sunni heartland, which shares a porous border with Syria.
Violence has intensified as Sunni opposition has swelled, and Iraq's al Qaeda affiliate has urged the protesters to take up arms against the government.
Security experts say al Qaeda-linked militants have been regrouping in the western province of Anbar and crossing into Syria to fight alongside mainly Sunni rebels against forces loyal to President Bashar al-Assad, an ally of Shi'ite Iran.