A Yemeni security official says two soldiers have been killed and two others wounded after a bomb placed under their car exploded at a checkpoint in the capital, according to AP. The official said Saturday's explosion in Sanaa also wounded a passer-by. The official spoke on condition of anonymity according to regulations. No group immediately claimed responsibility for the attack. Local al-Qaida militants have been carrying out attacks against security personnel as part of an offensive challenging the government of President Abed Rabbo Mansour Hadi. The U.S. considers the local al-Qaida branch, known as al-Qaida in the Arabian Peninsula, as being one of the world's most dangerous. The U.S. has helped Yemen intensify its campaign against militants and is believed to have conducted drone strikes there.