Gunmen allegedly affiliated with Al-Qaeda executed eight young Shiites but spared Sunnis after rounding up a group of men near a northern Iraqi town, a police official and a local politician said.
Four policemen were later wounded by a roadside bomb which exploded when they went to investigate the killings on a road between the towns of Amerli and Suleiman Bek, said Lieutenant Colonel Jassim al-Bayati, who was among the wounded.
The victims were aged between 16 and 20, Bayati said, adding that the roadside bomb at the scene was hidden under one of their corpses.
Ali Hashim Oghlo, a Salaheddin provincial council member, confirmed the account.
The attack comes just a day after gunmen riding motorcycles shot dead six young Arab men from Amerli while they were swimming.
While violence has decreased from its peak in 2006 and 2007, attacks remain common across Iraq. There were attacks on 27 of the 31 days in July.
Official figures put the number of people killed in attacks in July at 325, the highest monthly death toll since August 2010.