A suicide bomber wearing the uniform of Iraq's high-profile Wolf Brigade police force killed eight officers and wounded many others at the commando unit's Baghdad headquarters today.
Various police officials put the total number of dead and injured at close to 20.
Body parts littered the barracks area close to the Interior Ministry and police academy which houses the Wolf Brigade, a military-style force of several hundred mainly drawn from the capital's Shi'ite poor.
Promoted on television by a charismatic founder, the Brigade has denied accusations it has killed Sunni Muslims from the minority which ran Iraq under Saddam Hussein.
In the south of Baghdad, gunmen opened fire on a bus filled with labourers just, killing 10 people and wounding three.
A police official said the bus was carrying 13 people and travelling from the southern town of Hilla to Baghdad when two cars pulled up on either side and the gunmen attacked.
In a later attack, a suicide bomber in a pick-up truck blew himself up outside the Slovak embassy in Baghdad, wounding four people.
A police official said no Slovak staff were in the embassy and that the wounded were Iraqi civilians and guards.
Insurgents have stepped up attacks since Iraq's new government was formed in late April, killing over 800 people.