Four suicide bombers attacked two different mosques during noon prayers on Friday at Sanaa, the capital of Yemen, killing over 120 and wounding 260, according to multiple reports.
Another suicide bomber is reported to have blown himself up as well at Saada, but the bomb was allegedly detonated prematurely, killing only the attacker and no one else.
According to a pro-Islamic State Twitter account, the militant group claimed responsibility for the attacks.
"Let the polytheist Houthis know that the soliders of the Islamic State will not rest and will not stay still until they extirpate them," the Islamic State supporters quoted the group on Twitter. "God willing, this operation is only a part of the coming flood."
Though the White House condemned the attack, it did not say whether there are any confirmed reports that the attacks were indeed carried out by Islamic State militants.
Josh Earnest, the White House press secretary, pointed out that the Islamic State sometimes claims responsibility for attacks for 'propaganda value.'
The Islamic State also claimed responsibility for a recent attack in Tunisia, during which at least 23 were killed and 40 were wounded.
Meanwhile, Yemen has been undergoing much tension militarily and politically, due to two groups that support two different political ideas and leaders--a Houthi rebel group, a minority group which adheres to Shi'ite Islam, and Hadi, Yemen's current leader and an adherent to Sunni Islam.
Mosques in Sanaa are known to be used by Shi'ite Muslims like the Houthis, which Sunni Islam extremist groups such as al-Qaeda have targeted before. The Islamic State also follows Sunni Islam.
According to an Al Jazeera report, al-Murtada bin Zayd al-Mahatwari, a well-known Houthi imam and cleric, was also killed during this attack.
