Story highlights Four others also wounded Friday by gunmen at a checkpoint in Diyala province

June has been more violent than April or May; nearly 200 people have been killed this month

In May, the number was 132

Sectarian attacks peaked between 2005 and 2007

Four Awakening Council members were killed and four others were wounded Friday when gunmen attacked a checkpoint in Diyala province, about 40 kilometers (25 miles) north of Baghdad, police said.

The checkpoint was manned by members of the local Awakening Council in the town of Khan Bani Saad, according to police.

The councils, also known as Sons of Iraq, are composed predominantly of Sunni Arab fighters who turned on Iraq's al Qaeda militants in late 2006.

In another attack, seven people were killed and 45 others wounded when three explosions hit central Balad on Friday afternoon, police officials said.

The first attack was a suicide bomber who detonated his explosive vest in a busy outdoor market in the town of Balad north of Baghdad.

A few minutes later, two motorcycles rigged with explosives exploded near government offices, including a post office and a police station.

Police said most of the victims were from the suicide attack in an outdoor market near a Shiite Shrine

Balad is a predominately Shiite town in Salaheddin province.

Police officials in Baghdad said they believe al-Qaeda in Iraq is behind Balad attacks as they have been trying to agitate the sectarian tension between Arab Muslims Sunni and Shiite.

The officials told CNN on condition of anonymity because they are not authorized to speak to media.

In June, nearly 200 people were killed, according to CNN estimates.

In May, 132 people were killed. And 126 died in April, according to figures released by Iraq's Interior Ministry.

Overall, violence in Iraq has dropped since sectarian attacks peaked between 2005 and 2007, but bombings and shootings are still common.