Al-Qaida in the Arabian Peninsula has claimed responsibility for an attack on a Yemeni military hospital adjacent to the Defense Ministry that killed 52 people Thursday.
A statment issued on Twitter Friday that the group attacked the Defense Ministry building complex in the capital Sana'a because it "accommodates drone control rooms and American experts."
Thursday's two-stage attack began with a suicide car bombing followed by an attack by gunmen. Officials said the bomber rammed a car packed with explosives into one part of the complex as attackers on foot opened fire with automatic rifles on another.
It was the deadliest attack in more than a year. Casualties included civilians as well as military and medical personnel at the hospital. Yemen's Saba news agency said two doctors from Germany, two from Vietnam and another from Yemen were killed, as well two female nurses from the Philippines and one from India.
Yemeni President Abd-Rabbu Mansour Hadi later visited the compound, met senior military officials and ordered an investigation into the attack.
In Washington, a National Security Council spokesperson said the U.S. condemns the operation and "extends its deepest condolences to the families of the victims of this brutal attack."