Islamic State militants reportedly have burned to death 45 people in the western Iraqi town of al-Baghdadi on Tuesday, just five miles away from an air base staffed by hundreds of U.S. Marines.

The identities of the victims are not clear, the local police chief told the BBC, but some are believed to be among the security forces that have been clashing with ISIS for control of the town. ISIS fighters reportedly captured most of the town last week.

Col. Qasim Obeidi, pleading for help from the Iraqi government and international community, said a compound that houses families of security personnel and officials is now under siege.

The reports come days after ISIS released a video purportedly showing the beheadings of 21 Egyptian Coptic Christians along a beach in Libya, sparking an international outcry, including commendation from Pope Francis, who called the killings “barbaric.”

Two weeks ago, ISIS also burned a Jordanian pilot alive after holding him hostage since December.

Al-Baghdadi is only about five miles from Ain al-Asad air base, in the western province of Anbar, where 400 U.S. military personnel are training Iraqi soldiers and Sunni tribesmen to take on ISIS. The base was raided last week by a small band of fighters, in what some experts believe may have been a probe in preparation for a full-scale attack.

The base has been the target of sporadic mortar fire in past weeks, and the jihadist army has been moving forces from its strongholds in Syria to Anbar Province, possibly setting the stage for a major clash with forces on the base that is now the sole bulwark between ISIS and Baghdad.

There are currently nearly 2,600 U.S. forces in Iraq, including about 450 who are training Iraqi troops at three bases across the country, including al-Asad. Forces from other coalition countries conduct the training at the fourth site, in the northern city of Irbil.

But even if Islamic State militants close in on the base, taking it would require a massive force, that would present a target for airstrikes, retired Col. Thomas Lynch, a National Defense University fellow, told Fox News.