BAGHDAD — An airstrike by a United States-led coalition hit a gathering of leaders of the Islamic State jihadist group in northwestern Iraq on Saturday, and Iraqi officials said they believed that a number of top militants had been killed.

An Iraqi security official and a military commander said that at least one strike had targeted a meeting near the town of Qaim, which is in Anbar Province, across the border from the Syrian town of Bukamal. The area is in the desert heartland of the territory the group has seized for its self-declared caliphate.

Both officials said that the strikes had killed many militants from the Islamic State, also known as ISIS or ISIL, including two of its regional governors. Rumors also swirled that the group’s leader, Abu Bakr al-Baghdadi, had been either wounded or killed. The officials said they had no confirmed information about Mr. Baghdadi’s presence at the meeting.