A bomb devastated a minibus carrying students to their final exams in Baghdad on Monday, one of a string of blasts across Iraq that killed 27 people just two days after the deadliest attack in more than a year, Reuters reported.
The explosions came as U.S. combat troops prepare to withdraw from Iraqi towns and cities by the end of June, sowing further doubts about the local security forces' ability to stand alone against a stubborn insurgency.
Blood and shattered glass covered the floor of the minibus in Sadr City in eastern Baghdad after a roadside bomb killed three high school students and wounded 12 others. They had been on their way to sit for final exams before the summer holidays.
"What did these students do to deserve this? They're not politicians, Americans or policemen to be attacked," said witness Mohammed Yezen.
Elsewhere in the capital, a roadside bomb in a market killed three people and wounded 30 in the northern Shaab district, police said, while a parked car bomb killed five people and wounded 20 in Karrada in the city center.
In Husseiniya, just north of Baghdad, a bomb exploded in a vegetable market on Monday evening, killing five and wounding 25 others. Four children were among the wounded.
The blasts came two days after a suicide truck bomb outside a mosque near the northern city of Kirkuk killed 73 people in the country's deadliest attack for more than a year.
Violence has broadly fallen in Iraq over the last year, but analysts have said attacks are likely to intensify ahead of a parliamentary election due in January.
Iraqi Prime Minister Nuri al-Maliki has built his reputation on cutting violence, and has lauded the partial withdrawal of U.S. troops. In Baghdad, authorities have started to remove the concrete blast walls that have blighted the city for years.
In the west of the capital, a suicide bomber blew himself up on Monday outside the municipal council building in Abu Ghraib, killing seven people and wounding 13, police said.
Baghdad security spokesman Major General Qassim Moussawi said five people were killed and 41 wounded in the bombings in the capital. He gave no explanation for the lower figure.
In more violence near Kirkuk, a roadside bomb killed a member of a Sunni Arab anti-Qaeda militia, police said. Also in the north, the army said a roadside bomb killed three soldiers near Khanaqin, a town claimed by Arabs and Kurds.
Maliki urged Iraqis on Saturday not to lose heart if insurgents exploited the U.S. pull-back to step up attacks. U.S. troops are due to leave Iraq completely by 2012 as part of a security pact signed by Baghdad and Washington last year.