TEHRAN (Press Shia) – A car bomb blast in Iraq’s central city of Samarra killed at least eight people, including two Iranian pilgrims, on Sunday, local officials said.

Suicide bombers driving ambulances packed with explosives detonated their vehicles at a checkpoint and a car park for Shiite pilgrims in two Iraqi cities on Sunday, killing at least 21 people and wounding dozens, officials said.

The twin terrorist attacks took place in Tikrit and Samarra.

In Tikrit, a bomber detonated his explosives-laden ambulance at the southern entrance to the city during the morning rush hour, killing 13 people, police and hospital sources said.

Another attacker detonated a vehicle in a car park for pilgrims visiting one of Shiite Muslims’ holiest sites, the shrines of Imam Hadi (AS) and his son Imam Hassan al-Askari (AS), 125 km north of capital Baghdad.

The bomb killed at least eight people, local officials said, including two Iranian pilgrims. The local operation command, a joint military and police unit, said the vehicle used in Samarra was also an ambulance, Reuters reported.

Authorities in both cities declared curfews, fearing possible further attacks.

Meanwhile, Head of the Iranian Red Crescent Society Relief and Rescue Organization Pirhossein Koulivand told Press Shia that the bomb blast in Samarra blew up a nearby bus carrying Iranian passengers.

He also voiced the Iranian rescue teams’ readiness to transfer the Iranians injured pilgrims to the country.

Given the threat posed by the Daesh (ISIL) terrorist group in Iraq, the Arab country’s security forces have stepped up security measures in Shiite-majority cities, particularly at religious sites, ahead of Arbaeen.

Arbaeen, which is one of the largest religious gatherings in the world, comes 40 days after Ashura, the martyrdom anniversary of the third Shiite Imam, Imam Hussein (AS).