Two suicide bombers struck in Yemen on Thursday -- one targeting a gathering of Shiite rebels in the country's capital and the other hitting a military outpost in the south -- in attacks that killed nearly 70 people, officials said.

The bombings underscored Yemen's highly volatile situation following last month's takeover of the capital, Sanaa, by the Shiite Houthi rebels whose blitz stunned the impoverished Arab nation on the southern corner of the Arabian Peninsula. The Houthis' push into Sanaa also prompted threats of retaliation from their Sunni militant foes in Al Qaeda's Yemen branch.

The Health Ministry said at least 47 people died and 75 were wounded when a suicide attacker set off his explosives on Thursday morning in central Sanaa.

The attacker targeted a gathering of Houthis and their supporters, mingling among the protesters as they were getting ready for the rally in the city's landmark Tahrir Street before he detonated his explosives, according to security and health officials. The officials spoke on condition of anonymity because they were not authorized to talk to media.

The second bombing took place on the outskirts of the southern port city of Mukalla in Hadarmout province when a suicide car bomber rammed his car against a security outpost, killing at least 20 soldiers and wounding 15, the officials said.

Hadarmout is one of several strongholds of Al Qaeda's Yemeni branch, considered by Washington to be the most dangerous offshoot of the terror network.

There was no immediate claim of responsibility for either attack, but both bore the hallmarks of Al Qaeda, which has for years staged suicide bombings against army troops, security personnel and government facilities.

In Sanaa, the dead and wounded were taken to three hospitals. At one of them, the Al-Moayed hospital, victims' body parts were piled up on the hospital floor, and two severed heads were placed next to two headless bodies. The body of a man was placed nearby, one of his legs next to it.

There were at least six children in critical condition and some of the wounded arrived in hospital badly burnt, missing an eye or a limb.

At the scene of the blast in Tahrir Street, one of Sanaa's busiest, blood pooled on the ground as volunteers scooped up body parts from the pavement. Sandals and other personal belongings of the victims were scattered about.

Last week, Al Qaeda in Yemen warned it would target the Houthis and called on the country's Sunnis to close ranks and fight the Shiite rebels.

The Houthis had called the Sanaa rally to protest President Abed Rabbo Mansour Hadi's choice for new prime minister, Ahmed Awad bin Mubarak. As the crisis escalated, the prime minister-designate asked Hadi early on Thursday to relieve him of the post.

But despite the suicide bombing and bin Mubarak declining the premiership, the rally went on later Thursday, with some 4,000 Houthis calling on Hadi to step down and chanting slogans against the United States and Saudi Arabia.

Rebel leader Abdel-Malik al-Houthi delivered a televised statement on Wednesday night, calling on supporters to rally Thursday against the choice of bin Mubarak. He said his group was surprised by the nomination, saying it came after Hadi met with the U.S. ambassador to Yemen. Al-Houthi called Hadi a "puppet" in the hands of foreign powers.

"Blatant foreign interference is a form of circumventing the popular revolution," he said.

The Houthis took control of Sanaa last month but a U.N.-brokered deal subsequently managed to bring an end to the fighting and street battles in the capital. The Houthi takeover of Sanaa followed weeks of protests by their supporters in the capital to press demands for a larger share in power and a change in government.

The Sept. 21 deal called for the appointment of a new head of government, and for armed Houthis to pull out of the city.

Bin Mubarak, 47, was the head of Hadi's office and had successfully led an effort by various political parties -- including longtime rivals -- to devise a political map for transition after the 2011 uprising.  One of the youngest politicians in Yemen, he emerged on the political scene during the uprising, which  eventually forced longtime leader Ali Abdullah Saleh to step down as part of a U.S. and Saudi-backed accord.

Saleh handed over to Hadi but continued to wield significant power behind the scenes, setting the scene for more political instability.

The Houthi offensive has also raised the specter of more divisions along sectarian lines in impoverished Yemen, and compounded the country's myriad of troubles with the emboldened al-Qaida and a growing secessionist movement in the south.