A senior official at Iraq's ministry of education has been shot dead outside his home in west Baghdad.
The killing comes a day after Bassam Qubba was assassinated
Director of cultural relations Kamal al-Jarrah was gunned down as he left for work in the Ghazaliya district.
The attack comes a day after interim deputy foreign minister Bassam Qubba was killed by gunmen in the capital.
At least four policemen were also killed on Sunday in a car bomb attack as their patrol passed near a US military camp in Baghdad.
Earlier, the US-led coalition headquarters in the city was hit in a suspected rocket attack. There were no reports of casualties.
The BBC's Barnaby Phillips in Baghdad says the message from the gunmen to anyone involved in the interim government is clear and chilling - that they are all targets and their lives are in danger.
Mr Jarrah was ambushed by unknown gunmen outside his home at 0730 local time (0330 GMT) on Sunday.
He died in hospital shortly afterwards.
Mr Qubba was assassinated on Saturday morning as he left for work in the al-Azimiya district of the city.
A few days earlier, deputy health minister Ammar Safar escaped an attempt on his life in the same district while he was on his way to the ministry.
Ezzedine Salim leader of the now dissolved Iraq Governing Council, was assassinated on 17 May in a car bomb attack.
The head of Iraq's border guards, General Hussein Mustapha, says he narrowly escaped an ambush on Saturday as his two-car convoy was shot at on a Baghdad highway.
A police chief said at least four policemen were killed in a car bomb attack outside the base of the US 1st Cavalry Division on Sunday.
Police Captain Abdul-Razzaq Kadhem said the attacker also died.
Earlier on Sunday, smoke was seen rising above the so-called Green Zone on the west bank of the Tigris River.
An official in the zone said it was a suspected rocket attack.
"There were no reports of injuries. It's still under investigation," the official was quoted as saying by the Associated Press.
The headquarters have frequently been attacked by insurgents. Last month, two Britons were killed in a rocket attack outside the heavily-fortified facility.