Security officials in Yemen say a suicide attacker in the southern city of Aden set off a massive car bomb on August 29 -- killing 25 pro-government troops who were preparing to travel to Saudi Arabia to fight along Yemen's northern border.
Yemeni authorities say the attack also wounded more than 60 people who were taken to three different hospitals in the area.
The car bomber attacked a staging area near two schools and a mosque in Aden where the troops were registering to join the expedition.
Saudi Arabia is trying to build a force and train up to 5,000 men for the operation.
Islamic State militants said one of their fighters was responsible for the suicide attack.
The extremist group also claimed that it killed 60 people in the attack.