Initial reports said that at least 10 people were wounded and were being ferried to hospitals.
Car-bomb and gun attacks against US allies, police and civilians in northern Iraq, meanwhiled, killed up to 53 people during the defence secretary's trip.
The violent events also coincided with the release of a seized diary and documents by the US military that it says show al-Qaeda in Iraq cracking under a Sunni revolt against its tactics.
The heaviest loss of life on Sunday occurred at a checkpoint at the entrance of a bridge in the district of Yathrib, on the outskirts of Balad, 80km north of Baghdad.
A suicide truck bomber attacked Iraqi police and awakening group members manning the checkpoint, killing 34 people and wounding 37 others, police said.
Security forces fired at the bomber but could not prevent him from detonating the explosives.
A nearby car market and other shops were destroyed.
The US said in a statement that the toll in Balad was 23 killed and 25 injured.
They would not say whether the blast was by a suicide bomber, but stated that it was a car bomb at an Iraqi checkpoint near a market in Balad.
US and Iraqi forces secured the area.
Elsewhere, two villages near the country's border with Syria were stormed by fighters allegedly linked to al-Qaeda in Iraq.
The group was repelled by awakening council members and Iraqi soldiers, but 22 people were killed in the clash.
This number included 10 assailants, six awakening council members, and four women and children, according to Sheik Fawaz al Jarba, the head of the Mosul anti-al Qaeda group.
Another attack occurred near Sinjar, about 100km west of Mosul, killing five members of a local awakening council.
The attackers struck a compound in the north of the country, where the awakening council members lived.
The US military said five other awakening council members were injured, while 10 of the assailants were killed.
Separately, a group of civilians were attacked in the province of Ninawa on Sunday, the military said.
Two men and one child were killed in the attack and two other men, two women and two infants were injured.
In yet another incident near Mosul, explosives on a tanker truck were detonated, killing four civilians.
The blast occurred in the southern outskirts of the city, near an army checkpoint.