ISIS leader Abu Bakr al-Baghdadi has reportedly been killed by a U.S. airstrike, an attack that left three other senior members of the militant group dead.

The ISIS leader was killed during an air strike in the city of Mosul, which ISIS forces took over this summer. A Pentagon spokesperson did not confirm the death, but thousands of social media users have passed around an unverified photo claiming to be the ISIS leader’s body. It was also reported by Iraqi News.

Pentagon spokesman Col. Steve Warren did say that any ISIS leaders “inside troop formations they are likely to be killed.”

Abu Bakr al-Baghdadi was known as the world’s “most powerful jihadi leader” and “the new Bin Laden.”

“The true heir to Osama bin Laden may be ISIS leader Abu Bakr al-Baghdadi,” wrote The Washington Post’s David Ignatius.

Many believe that as the leader of ISIS, Abu Bakr al-Baghdadi helped the group eclipse al-Qaeda both in power and relevance in the region.

“For the last 10 years or more, [al-Qaeda leader Ayman al-Zawahiri ] has been holed up in the Afghanistan-Pakistan border area and hasn’t really done very much more than issue a few statements and videos,” Richard Barrett, a former counterterrorism chief with the British foreign intelligence service, told Agence France-Presse. “Whereas Baghdadi has done an amazing amount — he has captured cities, he has mobilized huge amounts of people, he is killing ruthlessly throughout Iraq and Syria…. If you were a guy who wanted action, you would go with Baghdadi.”

The reported killing of ISIS leader Abu Bakr al-Baghdadi comes after the United States just took out a leader of the group al-Shabaab, a Somali terrorist group. The leader killed, Ahmed Abdi Godane, was responsible for a the attack in a Kenyan mall last year that killed 68 people and left 200 more injured.