Not less than 60 people have been killed after a suicide car bomb exploded at a military facility in the southern Yemen city of Aden.
Also hit was a training camp, used by the pro-government popular resistance militia.
Islamic State have claimed responsibility for the attack.
IS’s self-styled news agency Amaq told BBC that the group had carried out Monday’s attack.
It comes amid a fresh push to end Yemen’s 17-month old war between Saudi-backed government and rebels.
Some 2.5 million Yemenis have also been displaced as a result of the fighting.
Meanwhile, the government and rebels have responded positively to a new gulf-backed initiative to end the conflict.
The rebels, however said they were prepared to restart negotiations, provided the Saudi-led coalition stopped attacking and laying siege to territories held by them.
The last peace talks in Kuwait earlier in August collapsed.
The Saudi-led coalition has been carrying out air strikes in Yemen since March 2015 in support of the internationally recognised government of President Abedrabbo Hadi.
The International Committee of the Red Cross (ICRC) is set to make emergency aid flights into Yemen’s capital, Sanaa.
The ICRC has been given permission to land planes carrying staff and medical supplies in Yemen, which it said was facing a humanitarian emergency.
Fighting had intensified in the southern port of Aden, as government troops battle the Houthis.
About 500 people had been killed over the past two weeks in Yemen.
However, the ICRC is sending a cargo plane carrying vital medical supplies, and a small passenger plane of aid workers.
Eight Houthi fighters were killed in an air strike before dawn in the suburbs of the northern city of Saadah, home of the Shi’ite Muslim movement which spread from its mountain stronghold to take over the capital Sanaa six months ago.
Local officials said strikes also hit air defense and coastal military units near the Red Sea port of Hodaida, and targets on the outskirts of Aden. They also hit a bridge on the road south to Aden, apparently trying to block the Houthis from sending reinforcements to their fighters in the city.
Meanwhile, the cargo plane is still awaiting approval to send a surgical team by boat to Aden.
The ICRC has, however, called for a 24-hour ceasefire in Aden, while Russia has also urged the UN Security Council to support a “humanitarian pause” in the air strikes.
Pakistan’s parliament is debating whether to join the Saudi-led coalition after a Pakistani aircraft rescued 170 people from Sanaa on Sunday.