Bombings across Iraq, including a suicide blast at a college in north Baghdad, have killed at least 18 people, while clashes in the country's restive city of Fallujah left 15 people dead.
Sunday’s violence came less than two weeks before a parliamentary election that will be a major test for security forces.
Police officials said that a suicide bomber with an explosives belt attacked the main gate of a Shia private college in Baghdad's eastern neighbourhood of Ur, while three armed men attacked the back gate.
Four policemen and one teacher were killed while 18 people were wounded. The three gunmen were killed, according to the officials. Medical workers confirmed the causality figures.
All officials spoke on condition of anonymity as they were not authorised to release information.
Iraq is hit by daily bombings and shootings that kill hundreds of people each month, but attacks targeting universities are relatively rare.
Also on Sunday, two car bombs exploded simultaneously in a commercial area in the southern city of Samawah, killing seven civilians and wounding 17, police said. The Shia city is located 370km southeast of Baghdad.
In a third attack, a car bomb in a commercial area in the town of Iskandariyah south of Baghdad killed three civilians and wounded 12 others, police said.
There were no immediate claims of responsibility for the bombings, but Sunni armed groups have stepped up attacks across the country since the Shia-led government cracked down on a Sunni protest movement last year.
Fighting in Fallujah
Violence outside the capital, in particular, has increased as fighters look to undermine the government ahead of the parliamentary election on April 30.
More than 9,000 candidates will vie for 328 seats in parliament, but there will be no balloting in parts of the Sunni-dominated Anbar province, which is engulfed in clashes between security forces and al-Qaeda-inspired fighters.
The fighters have seized and are continuing to hold parts of the provincial capital, Ramadi, and nearly all of the nearby city of Fallujah.
Clashes between the army and fighters on Sunday in Fallujah left at least 15 people killed, of whom six were killed by an artillery fire, Al Jazeera's correspondent reported.
All entries into the city had been closed, the correspondent said.
Last year, Iraq weathered its deadliest bout of violence since it pulled back from the brink of civil war in 2008. UN figures show that violence killed 8,868 people in 2012.
Violence has killed more than 460 people in Iraq this month and upwards of 2,700 this year, according to the AFP news agency figures based on security and medical sources.