Three coordinated bomb attacks within minutes of each other Sunday morning hit the central city of Tikrit, 130 kilometers (80 miles) north of Baghdad, a provincial official said. A civilian walking by was killed and two others were wounded.
The bombs went off near a middle school where students were taking exams, but authorities said none of the students was hurt.
Further south, three policemen died when a suicide car bomb and three roadside bombs exploded at a security checkpoint on Saturday night in Samarra, 95 kilometers (60 miles) north of Baghdad, a police official said.
The officials spoke on condition of anonymity because they were not authorized to release the information.
The bombing Saturday night raised the death toll for June to at least 237, the second-bloodiest month since U.S. troops withdrew from Iraq in mid-December.
Most attribute the violence to al-Qaida-affiliated insurgents emboldened by political feuding that has paralyzed the government and hoping to reignite fighting among the country's ethnic and sectarian factions.
More significant than the numbers was the fact that insurgents appeared able to sustain the level of violence over a longer period than before.
There was a major bombing or shooting rampage almost every three days in June, many targeting Shiite pilgrims on their way to the annual Baghdad commemoration of a revered imam.
Another Shiite pilgrimage set for this week has security forces on high alert.
Hundreds of thousands of pilgrims are expected to travel to the holy city of Karbala, 80 kilometers (50 miles) south of Baghdad, for the festival of Shabaniyah, celebrating the birth of the ninth-century Shiite leader known as the Hidden Imam.
The pilgrimage peaks on Friday.