Baghdad: Gunmen killed three Sunni clerics near the mostly Shiite city of Basra in southern Iraq, a government spokesman said Friday, an apparent sectarian attack that drew immediate calls for calm.

Interior Ministry spokesman Sa’ad Ma’an told The Associated Press that the assailants ambushed a car Thursday night carrying the clerics in the mostly Sunni district of Bab Al Zubair near Basra, shooting dead the three and seriously wounding two other clerics traveling with them.

The ministry, he said, was investigating the killings. He gave no other details.

There was no claim of responsibility for the ambush and no reports of retaliatory attacks by Sunnis.

Iraq’s sectarian violence peaked in 2006-07, when thousands of Iraqis perished in attacks. The violence later eased but has partially resumed after Daesh swept across much of northern and western Iraq last year.

Shiites make up a majority of Iraq’s estimated 30 million people and have dominated successive governments since the 2003 ouster of Saddam Hussain.

The attack followed a visit to Basra this week by Prime Minister Haider Al Abadi. Al Abadi on both visits spoke emphatically about the need for all of Iraq’s religious and ethnic communities to close ranks in the face of the threat posed by the Islamic State group.

An association of Sunni clerics also called for calm in a statement issued Friday, arguing that the attack was carried out to ignite sectarian violence in Basra. Speaking later on state Iraqi television, the association’s head, Khaled Al Mullah, said Daesh and its supporters were the only beneficiaries of the attack.

In other violence Friday, a roadside bomb exploded in central Baghdad, killing four civilians and wounding 12, police and hospital officials said. They spoke on condition of anonymity because they were not authorized to speak to journalists.