Two brutal incidents in Iraq, in which one saw decapitated heads being strewn in a marketplace, killed nine people on Sunday.
The second incident involved militants forced Shiite policemen to pray before killing them, Agence France-Presse reported.
Both took place in the Salaheddin province, north of Baghdad, security and medical officials told the news agency. In one ethnically-mixed town, militants surrounded a police encampment protecting a stadium construction site and gathered the six policemen as a group and shot them all dead, two security officials and a doctor at the local hospital told the news agency.
One of the six, however, only died at hospital, and according to a local Tuz official, said that the insurgents had attempted to find out if the policemen were Sunni or Shiite before killing them.
The policemen were allegedly asked which which sect they belonged to and the policemen, who were Shiite Turkmen, initially said they were Sunni in an effort to save themselves, the town official said, speaking on condition of anonymity to AFP.
In the separate incident in Baiji, the decapitated heads of three men were found in a town market Sunday morning, two police officers in the town said.
The men -- an anti-Qaeda militia chief, his son and his cousin -- were kidnapped late on Thursday near provincial capital Tikrit, according to AFP.
The militiamen, known as the Sahwa, joined forces with the U.S. military against their co-religionists in Al-Qaeda from late-2006 onwards, helping turn the tide of Iraq's violent insurgency.
But, as a result, they are regarded as traitors by Sunni militants and often targeted in attacks.
Violence has surged in Iraq in recent months to levels not seen since 2008, with more than 1,000 people killed in January alone, according to government figures.