Islamic State spokesman Abu Hassan al-Muhajir, considered a potential successor to terror leader Abu Bakr al-Baghdadi, also was killed in Syria in a separate attack by U.S. forces, a senior State Department official confirmed to Fox News on Monday.

Al-Muhajir had been considered a “number two” to al-Baghdadi, according to the official.

The second U.S. military operation took place in Turkish-held Jarabulus in northern Syria, a 3-hour drive from where al-Baghdadi was killed near another border town with Turkey, Fox News has learned.

AL-BAGHDADI KILL: HOW THE DARING MILITARY OPERATION WENT DOWN

Hours after U.S. Special Operations forces raided al-Baghdadi’s compound in northwestern Syria, the top Kurdish leader for the Syrian Democratic Forces, Gen. Mazloum Abdi, tweeted: “Following the previous ops, a senior assistent for al- Bagdadi is called Abu Hesen al Mouhjir was targeted in a village named Ein al Baat near Jaraboul city, the mission was conducted via direct coordination of SDF Intel & US military apart the ongiong ops to hunt ISIS leaders.”

Al-Baghdadi was killed during Saturday night’s daring raid in Syria and after years of intelligence gathering, U.S. Special Operation Forces had no doubts the mutilated body of the man killed during that raid was the long-sought ISIS leader. U.S. Special Operation Forces employed new technology and DNA testing to positively identify al-Baghdadi's headless remains almost immediately.

TRUMP DEFENDS KEEPING 'LEAKER' SCHIFF, PELOSI OUT OF THE LOOP ON AL-BAGHDADI RAID

While the commandos had visually identified al-Baghdadi before he bolted down a dead-end tunnel with three children -- where he was found "whimpering" and trapped before detonating a suicide vest -- that wasn’t enough. Various accounts have told of his death in the past, only for him to surface yet again.

“There wasn’t much left,” President Trump said of al-Baghdadi’s remains during a Sunday morning news conference following the raid, “but there are still substantial pieces that they brought back.”

Al-Baghdadi’s head remained intact following the blast, allowing commandos to use biometrics, specifically facial recognition, to immediately identify him, Fox News National Correspondent Jennifer Griffin reported.

Biometrics is a method of authenticating a person’s identification that uses human features such as fingerprints, facial recognition or other physical characteristics.

WHO'S LEADING ISIS NOW THAT AL-BAGHDADI IS DEAD?

The U.S. military operation that killed the elusive ISIS leader also succeeded in decapitating the organizational structure of the international terror group facing a leadership vacuum in the latest of several major setbacks.

While it remains unclear who exactly will take over the terror organization, President Trump said in March the caliphate was “obliterated” and the U.S. will “continue to pursue the remaining ISIS terrorists to their brutal end.”

The terror group has yet to officially name a successor.

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The terror group already had lost vast stretches of its physical caliphate that stretched across parts of Syria and Iraq, but counterterrorism experts have cautioned they expect the group's ideology to endure beyond al-Baghdadi.

Fox News' Lucas Tomlinson, Stephen Sorace and The Associated Press contributed to this report.