Elsewhere, four people were killed in an attack on the offices of Iraq's largest Sunni political party.
Police and officials from the Iraqi Islamic Party confirmed the attack on the party’s offices in the northern city of Mosul.
Mohammed al-Wagga from Mosul police said: "The bomb exploded after midnight in the office in central Mosul's Al-Zizlani district."
Ten Baghdad commuters were killed and eight wounded when their minibus was hit by a bomb.
The passengers were killed as their bus passed by Mustansiriyah University.
Conflicting reports from interior and defence officials blamed the blast on a roadside bomb or a passenger wearing an explosives-laden vest.
Five labourers were killed and ten wounded in an attack on their bus near Baladruz, 100km northeast of Baghdad in the Diyala province.
Two women were killed when their car was hit by a roadside bomb in Mahmudiyah, south of Baghdad, police said.
Another woman and an infant were wounded.
Two civilians were killed when unknown gunmen shot them south of Baghdad in the district of Mashru, police said.
In another incident, two policemen were killed and seven others were wounded as a roadside bomb they were defusing in the Zulf-al-Sakhar district between Baghdad and the central city of Hilla exploded.
The US military, meanwhile, announced the arrest of 15 suspects in a series of raids that they said targeted al-Qaeda networks in Iraq.