Gunmen travelling in three cars have opened fire in a Baghdad market, killing at least six pedestrians, police and medics say.
At least 16 people were wounded when the drive-by shooting happened in the southern Zaafariniya area of the city.
Earlier, a barrage of fire had hit the city's heavily fortified Green Zone.
In further violence, at least 13 Iraqi soldiers were killed in a suicide bomb attack on an army base in the northern city of Mosul.
The gunmen who mowed down shoppers in south Baghdad are reported to have fled the scene.
A medic at Ibn Nafis hospital confirmed receiving six bodies of people killed in the attack, reported AFP news agency.
Elsewhere in Iraq, at about 0700 (0400 GMT), 13 soldiers died and about 30 people were injured in a huge blast in Mosul, caused by an explosives-laden tanker which ploughed into the army base.
Iraqi and US soldiers have been engaged in a major offensive in Mosul, the scene of intense insurgent activity in recent months.
US commanders say Mosul is al-Qaeda's last urban stronghold in Iraq, and in January the Iraqi Prime Minister, Nouri Maliki, announced the start of a major counter-insurgent offensive.
According to AFP, witnesses said Iraqi forces had sealed off the area around the base, in the Hermat neighbourhood of west Mosul.
Military planes and helicopters were seen hovering above the base.
Early on Sunday, a series of 10 or 12 rockets or mortars were fired into the Green Zone one - home of the Iraqi government HQ, the US and UK embassies, and thousands of American troops - at about 0600 (0300 GMT).
As the barrage hit the Green Zone, the US public address system warned people "to duck and cover" and to stay away from windows.
The barrage of rocket or mortar fire sounded like successive peals of thunder in an audio recording of the attack.
No casualties were reported in the attack, which left a shroud of stinking black smoke over the city, reports the BBC's Adam Brookes.
Previous rocket attacks on the Green Zone have been blamed on rogue elements of Moqtada Sadr's Mehdi Army militia.
Moqtadr Sadr renewed a ceasefire for his militia last month.
Security in Iraq has improved overall since last June, when the US deployed an extra 30,000 troops in violence-hit areas.
But our correspondent says the number of high-profile attacks has been creeping back upwards in recent months.