Sunni militants killed 19 Shiite militiamen in an ambush north of Baghdad on Wednesday, officials said.

Police officials said fighters from the Islamic State extremist group hiding in orchards opened fire with machine-guns on a convoy of Shiite militiamen travelling on a road in Babilan village. They said 39 other people were wounded in the attack.

Babilan is about 60 miles north of Baghdad.

Thousands of Iraqi Shiites answered a call from clergy in June to join security forces fighting the Sunni militants, who have captured large swaths of land in the country's west and north. The re-activation of Shiite militias has raised fears of a return to the sectarian violence that convulsed the country in 2006 and 2007.

In other violence, police said three separate bombings in commercial areas of the capital killed seven people and wounded dozens of others.

Medical officials confirmed the casualty figures from all attacks. All officials spoke on condition of anonymity as they were not authorized to release information.