The defense official said it appears that Baghdadi detonated a suicide vest during the raid.
The raid carried out by special operations commandos, a source familiar with the operation told CNN.
The CIA assisted in locating the ISIS leader, the defense official said.
Newsweek first reported that forces believe they have killed Baghdadi.
President Donald Trump scheduling to make a major announcement Sunday at 9 a.m., White House deputy press secretary Hogan Gidley announced. An administration official tells CNN that the announcement is foreign policy related.
The Pentagon did not immediately respond to a request for comment.
Who was Baghdadi?
Baghdadi, the leader of the terror group, has been in hiding for the last five years. In April, ISIS media wing al-Furqan published a video that showed a man purporting to be Baghdadi. It was the first time everybody saw Baghdadi since July 2014, when he spoke at the Great Mosque in Mosul.
In February 2018, several US officials said Baghdadi had been wounded in an airstrike in May 2017 and had to relinquish control of the terror group for up to five months because of his injuries.
Baghdadi became the leader of Islamic State of Iraq (ISI) in 2010. In 2013, ISI declared its absorption of an al Qaeda-backed militant group in Syria and Baghdadi said that his group will call itself as Islamic State in Iraq and the Levant (ISIL or ISIS).
White House officials were at the White House late Saturday evening in preparation.
One official told CNN the announcement then will go on in the Diplomatic Reception Room.
Trump stoked speculation when he tweeted Saturday evening “something very big has just happened!”