Baghdad, Jul 22 (IANS): Three brothers and one of their relatives were killed in an attack by Islamic State (IS) militants in Iraq's eastern province of Diyala, a provincial police source said.

IS militants opened fire at a group of young men swimming in the Diyala River in the town of Maqdadiyah on Thursday, some 100 km northeast of the Iraqi capital Baghdad, Xinhua news agency reported, citing Major Alaa al-Saadi of the police provincial command.

The three brothers were killed on the spot, and their relative later died in a hospital, al-Saadi said, adding that another relative of the brothers was also wounded in the attack.

Iraqi security forces rushed to the scene and launched a search campaign looking for the attackers, al-Saadi said.

Over the past few months, Iraqi security forces have conducted operations against the extremist militants to crack down on their intensified activities.

The security situation in Iraq has been improving since 2017 after defeating the IS. However, the IS remnants have since melted into urban centers, deserts and rugged areas, carrying out frequent guerilla attacks against the security forces and civilians.