RIYADH — Two Saudi soldiers have been killed in a clash with unidentified gunmen who fired on them from across the border with Yemen, the Interior Ministry said Thursday. A Border Guard patrol in the Dhahran Al-Janoub sector in the southwestern province of Asir “came under heavy gunfire on Wednesday morning from unknown sources inside Yemeni territory,” the ministry's security spokesman said. The attack triggered a gun battle, which resulted in the death of Sgt. Abdulrazaq Al-Ghamidi and soldier Mohammed Al-Qahtani, he said in a statement. He said they would be treated as martyrs in the line of duty. The Saudi authorities were coordinating with their counterparts in Yemen to investigate the attack.