Medics transport an injured Yemeni man on a gurney as he arrives at a hospital in Sanaa after being injured when two suicide bombers hit a Shiite mosque in the Yemeni capital in quick succession on September 2, 2015.

The Islamic State of Iraq and Syria claimed responsibility for two bombings at a mosque in a northern district of the Yemeni capital Sanaa on Wednesday.

Media sources affiliated with the Houthis claim that at least 28 people were killed in the attacks.

The al-Mo’ayyad mosque, run by the Houthis in the al-Jarraf neighborhood of Sanaa, has previously been targeted by the ultra-radical ISIS, who regard the Iran-allied Houthis as heretics.

The Houthi-controlled Saba news agency said in a text message that the first explosion was caused by a suicide bomber in the al-Mo’ayyad mosque, followed by a car bomb blast that targeted medics outside the building.

A civil war in Yemen escalated in March when a coalition of Arab states led by Saudi Arabia intervened to roll back the hold of Iran-allied Houthi militia over much of the country and to reinstate the government from its exile in Riyadh.

The Houthis took control of the capital Sanaa a year ago. More than 4,500 people have been killed in the Arabian Peninsula country’s conflict.

Earlier on Wednesday, two Red Cross employees were shot dead in the northern Yemeni province of Amran by an unknown attacker, the international aid group said, in a rare case of violence against humanitarian workers in the war.