BAGHDAD — Deadly attacks in Iraq killed at least 33 people Sunday, including a dozen children slain when a suicide bomber detonated the explosives-laden car he was driving near their elementary school in the north of the country, officials said.

The attacks are the latest in a relentless wave of killing that has made for Iraq’s deadliest outburst of violence since 2008. The mounting death tolls are raising fears that the country is falling back into the spiral of violence that brought it to the edge of civil war in the years after the U.S.-led invasion in 2003.

Sunday’s blasts began around 9:30 a.m. in the Shiite Turkomen village of Qabak. One car bomb in the tiny village targeted an elementary school while children ages 6 to 12 were in class, and another struck a nearby police station, Tal Afar mayor Abdul Aal al-Obeidi said. The dead included 12 children, the school principal and two policemen.

“We and Iraq are plagued by al-Qaida,” al-Obeidi said. “It’s a tragedy. These innocent children were here to study. What sins did these children commit?”

Another suicide bomber, this time on foot, blew himself up hours later as Shiite pilgrims walked through the largely Sunni neighborhood of Waziriyah in the north of the Iraqi capital. At least 12 people were killed and 23 wounded in that attack, according to police and hospital officials.

Later Sunday, a bomb hidden in a parking lot exploded in Baghdad al-Jadidah, a district in the east of the Iraqi capital that has both Sunni and Shiite areas. That blast killed six and wounded 12, officials said.

There was no immediate claim of responsibility for the latest attacks, but suicide bombers and car bombs are frequently used by al-Qaida’s Iraq branch. It often targets Shiite civilians in an effort to undermine the Shiite-led government. Its extremist ideology considers Shiites heretics.