ISIS leader killed while fighting, successor named

He was reportedly killed while fighting recently, though further details were given in the message and no one has claimed responsibility for the killing.

The U.S. military says that the leader was killed in mid-October during a operation conducted by Syrian rebels, but it is unknown why they waited until now to announce the death.

"I announce and mourn for the Islamic state and the fighters of almighty Islamic state, (the absence) of the Amir of believers and the Calipha of the Muslims Abu al-Hasan al-Hashmi al-Qurayshi … he was killed while struggling against the enemies of God," a spokesman for the group said in a message released Wednesday.

The militant group also announced that its new leader is Abu al-Hussein al-Husseini al-Qurashi, described by the group simply as an "old fighter."

Al-Qurayshi's death marks the second time this year that an ISIS leader has been killed. His predecessor, Abu Ibrahim Al-Hashimi Al-Qurayshi, was killed in February during a raid by U.S. forces.

"ISIS remains a threat to the region," the U.S. Central Command said on Wednesday. "CENTCOM and our partners remain focused on the enduring defeat of ISIS."

It was reported last month by the Syrian Observatory for Human Rights that a group of Syrian rebels, who has recently reconciled with their government, killed a group of Islamic State fighters in the south of the country.

The miltant Islamic group has been making attempts to rise again recently. Its sleeper cells in Iraq and Syria have carried out deadly attacks recently, and its affiliate in Afghanistan has also claimed responsibilty for attacks that have killed dozens of people.

A bomb blast on Wednesday at a school in Afghanistan killed at least ten students. ISIS haven't specifically claimed responsibility for the attack, but officials believe it to be from the group.