Aden (Yemen):  Triple suicide bombers hit a pair of mosques crowded with worshippers in the Yemeni capital, Sanaa, on Friday, killing 137 and injuring 345 people, according to medical officials. The attackers targeted mosques controlled by Shiite rebels. A group claiming to be a Yemeni branch of the Islamic State group says it carried out the suicide bombings.

A report on the rebel-owned Al-Masirah TV channel said the bombers attacked the Badr and al-Hashoosh mosques during midday prayers on Friday, traditionally the most crowded time of the week. There was no immediate casualty report. It added that hospitals were urging citizens to donate blood.

Witnesses said that at least two suicide bombers attacked inside the Badr mosque. One walked inside the mosque and detonated his device, causing panic as dozens of worshippers rushed toward the outside gates. A second suicide bomber then attacked amid the panicked crowds trying to escape.

One witness at the al-Hashoosh mosque, located in Sanaa's northern district, said that he was thrown two meters away by the blast.

"The heads, legs and arms of the dead people were scattered on the floor of the mosque," Mohammed al-Ansi told The Associated Press, adding, "blood is running like a river."

Al-Ansi added that many of those who didn't die in the explosion were seriously injured by shattered glass falling from the mosque's windows. He recalled running for the door along with other survivors and hearing one man screaming, "come back, save the injured!"

The Shiite TV network aired footage from inside al-Hashoosh mosque, where screaming volunteers were using bloodied blankets to carry away victims. One of the dead included a small child. Corpses were lined up on the mosque floor and carried away in pick-up trucks.

The attacks come a day after intense gun battles in the southern city of Aden, between rival troops loyal to Yemen's former and current president, left 13 dead and forced closure of the city's international airport.

The Shiite rebels, known as Houthis, swept down from their northern strongholds and seized the capital in September. Allied with ousted former Yemeni president Ali Abdullah Saleh, they now control at least nine of Yemen's 21 provinces. Earlier this year they put Abed Rabbo Mansour Hadi, the western-backed president, under house arrest. Hadi has since fled to the southern city of Aden, where he established a temporary capital and maintains he is still the legitimate president.