The Islamic State has claimed responsibility for a set of coordinated suicide bombings in Yemen today that has so far killed more than 137 people and injured an estimated 350.

The attacks were both carried out at mosques in Yemen's capital city of Sanaa used by Iran-supported Shi'ite Houthi fighters during their morning prayer service.

"Let the polytheist Houthis know that the soldiers of the Islamic State will not rest and will not stay still until they extirpate them," the Islamic State said on a supporter-run Twitter account. "God willing, this operation is only a part of the coming flood."

According to eyewitness reports, there were two successive explosions on two separate mosques led by four attackers. An additional bomber reportedly had a misfire of his bomb, causing it to explode prematurely with no casualties but himself. This is thought to be the deadliest attack on Yemen's civilians since January when a car bomb killed 30 people outside a police station.

"I was going to pray at the mosque then I heard the first explosion, and a second later I heard another one," a witness told Reuters.

The group claiming responsibility calls itself Sana Province and is considered the Yemeni branch of the Islamic State. Yemen has been the subject of intense fighting in the last seven months that is quickly approaching a civil war status between the Shi'ite Houthis and the Sunni militants.

In January, the Houthis took over the Yemeni capital and ousted president Abdu Rabbu Mansour Hadi, placing him under house arrest along with his government. When Hadi fled to the southern port city of Aden, he claimed that he still controlled the country, but the fighting and division has only intensified. With Hadi there, Aden is now the target of severe fighting, including warplane bombings of the presidential compound.

A separate audio message was also posted on ISIS-affiliated websites claiming that five Islanic State suicide bombers killed dozens of "Houthi infidels." The voice is said to be the same voice used on an audio message claiming responsibility for Thursday's attack on the Bardo museum in Tunisia.

Among those killed in the Sanaa bombings was prominent Houthi religious leader Murtatha Al Mahathwari, and officials say that this type of targeting means that ISIS may have more presence in the area than suspected. 

"The dominant group there is al Qaeda in Yemen. ISIS and al Qaeda in Yemen can't stand each other," CNN terrorism analyst Paul Cruickshank said. "But ... whoever is responsible, I think, (is) trying plunge the country into civil war."

The hospitals in the Yemeni capital are overwhelmed by the dead and injured, and aid workers are currently pleading for blood donations. 

Despite the claim of responsibility by the Islamic State, the White House said it can not acknowledge blame until the identities of the bombers are positively identified as those directed by the Islamic State.