Gunmen killed six young Arab men while they were swimming in a predominantly Turkmen town in north Iraq on Saturday, security and medical officials said.
"The six martyrs were Arab residents from Amerli," said Colonel Khalid Hassan al-Bayati, police chief of the town of Tuz Khurmatu, 175 kilometres (110 miles) north of Baghdad.
Amerli lies just outside Tuz Khurmatu, which is mostly populated by Shiite Turkmen.
"This is a terrorist act, not a criminal act. Two gunmen attacked them while they were swimming," Bayati said.
A police lieutenant colonel said the attackers were riding motorcycles and had fired on the group while they were in a pool in Tuz Khurmatu.
A doctor in the town's hospital confirmed receiving the six bodies, adding that all had suffered multiple gunshot wounds.
The latest violence brings the number of people killed in attacks in Iraq so far this month to at least 113, including 57 security forces members, according to an AFP tally based on security and medical sources.
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.