Eighteen Iraqis were shot dead in execution-style killings hours after being abducted from their homes near Baghdad, police said.
Authorities said their bodies were found in an orchard near the Sunni-dominated town of Mishahda, some 30 km (20 miles) north of the Iraqi capital. Police said the men had been shot in the head.
A Sunni tribal chief and his son were among the victims, which also included a police officer, an army official and the headmaster of a school.
The 18 were each pulled into four SUVs by men wearing army uniforms late in the evening, eyewitnesses said.
No-one has so far claimed responsibility for the killings. Militants disguised as security officers are known to have conducted kidnappings in the area in the recent past, Reuters reported.
A senior police official said al-Qaida carried out the killings in retaliation for the Sunni men's support of Iraq's Shi'ite-led government.
"It is definitely al-Qaida because this is the area where they are operating," the official, who spoke on condition of anonymity, told Reuters.
The grim discovery was followed shortly by two bombings in Baghdad.
Three people were killed and six wounded as a bomb went off inside a sheep market in Baghdad's southeastern suburb of Nahrawan.
A second explosive device was detonated in the western Abu Ghraib suburb, killing one and injuring five.
A cluster of Sunni militant groups, including al-Qaida, have increased attacks against the Shi'ite-led government, embarking on a spree of deadly bombings.
The attacks have fuelled an outbreak of sectarian violence that threatens to push the country back into civil war, as it did in 2006 and 2007, when both Shi'ite and Sunni Muslim militant groups were active parts in a bloodshed that saw thousands killed.
According to the UN more than 5,500 people have been killed in ethnic violence since April.