Two car bombs have exploded in the northern Iraqi town of Tal Afar, causing heavy loss of life.
A grieving woman at the scene of the killing of Wael Rubaie
Officials said at least 20 people were killed in the attack, and others were trapped as a building collapsed.
The attacks came at the end of a day of violence in Iraq, that included bomb attacks on a mosque and a restaurant, which killed at least 24 other people.
In another incident, the commander of a new unit set up to fight insurgents was shot dead in the capital, Baghdad.
The bombs in Tal Afar went off outside the home of a community leader, Hassan Baktash, who has links with Massoud Barzani's Kurdistan Democratic Party.
The explosion brought the building crashing down.
"I don't have a final number for the dead or wounded but it's between 20 and 30," a police source told Reuters, adding "some are still trapped."
Elsewhere, a car bomb exploded outside a Shia mosque in Mahmoudiya, a town south of Baghdad. At least seven people were killed and more than 20 injured.
Doctors said many of the casualties were children.
"The kids were playing outside the mosque when a car came up quickly and then exploded," said a witness, Mohammed Awad.
Earlier on Monday, another car bomb went off outside the popular Habayibna restaurant in the Shia-dominated Talibiya area of Baghdad.
The attack came during a busy time for the restaurant.
At least eight people were killed in the blast and as many as 100 were injured. Several cars parked outside were set ablaze.
In Tuz Khurmatu in northern Iraq, a car bomb exploded killing five and wounding 13 others.
The attack happened near the council offices in the town, 88km (55 miles) south of Kirkuk, police said.
In central Iraq, two suicide bombers detonated car bombs outside a military base in the town of Samarra, 95km (60 miles) north of Baghdad.
Reports say eight died and dozens were injured in Baghdad
A third attacker approached the base carrying explosives and was shot by soldiers, the US military said.
Iraqi police said two Iraqi men were killed and six wounded, including women and children. The US military said three soldiers sustained injuries that were not life threatening.
In Baghdad, Iraqi officials said Wael Rubaie, head of operations at the Ministry for National Security, and his driver were killed on their way to work.
Maj Gen Rubaie had been recently appointed to command a special operations room set up to co-ordinate the fight against insurgents across all Iraqi ministries and with the US-led multinational force.
More than 550 people have been killed in Iraq in less than a month.