ADEN, Yemen: A group claiming to be a Yemeni branch of the Islamic State group says it carried out a string of suicide bombings in the Yemeni capital, Sanaa, that killed a total of 137 people and injured 345 others.

The group posted an online statement saying that five suicide bombers carried out what it described as a “blessed operation” against the “dens of the Shiites.” The bombers attacked the Badr and Al-Hashoosh mosques, located across town from each other, during midday Friday prayers.

Leading Houthi cleric Al-Murtada bin Zayd Al-Muhatwari, the imam of the Badr mosque, was among those killed, a medical source said.

The claim, posted in an online statement, could not immediately be independently confirmed and offered no proof of an IS role. It was posted on the same website in which the Islamic State affiliate in Libya claimed responsibility for Wednesday’s deadly attack on a museum in Tunisia.The Houthi militia’s Al-Massira television said hospitals in the capital had made urgent appeals for blood donations.Footage aired by Al-Massira showed bodies lying in pools of blood outside the mosques, as worshippers rushed the wounded to hospitals in pick-up trucks.

Another suicide bomber blew himself up outside a mosque in the northern Houthi stronghold of Saada, a source close to the militia said.

Only the assailant was killed in that explosion and tight security at the mosque prevented the bomber from going inside, the source added.

The Houthis overran Sanaa in September and have since tightened their grip on power.