One of the founders of ISIS’ propaganda arm reportedly was killed in his hometown during a coalition airstrike in eastern Syria.

Rayan Mash’al and his daughter were in their home Wednesday in the city of Al-Mayadin, part of Deir ez-Zor province, when coalition forces launched a bombing attack, according to the Facebook post Wednesday by Mash’al’s brother, Hozaifa Abo Alyaman, the Middle East Media Research Institute reported.

"I break the news to you of the death of my older brother Bara' Kadek, known as Rayan Mash'al, together with his daughter Lian, as a result of a coalition forces aerial bombing of his home in the region of Al-Mayadin in Deir ez-Zor," the post said.

Mash’al was one of the founders of the Halab news agency at the beginning of the rebellion in Syria before going on to co-found ISIS’ media division, known as the A’maq news agency, in 2013, according to an announcement of his death by the pro-ISIS Al-Haq media outlet.

The militant group itself has not reported the death of Mash’al.

It is through social media channels that ISIS often claims responsibility for terror attacks throughout the world. A’maq has become the terror group’s fastest and most reliable source of information, using it to post videos and claims of attacks. It has remained online despite bans from social media platforms.

Rita Katz, director of the U.S.-based SITE monitoring service, said on Twitter that a coalition strike allegedly killed [Mash’al] in Deir ez-Zor and that since its founding, A’maq claimed responsibility for at least two dozen attacks worldwide, according to Reuters.

There was no immediate comment from coalition forces.

Last week, the coalition told The Associated Press it had carried out a series of airstrikes on May 25 and 26 targeting the ISIS media infrastructure and “propaganda facilities.”

It said at the time that targeting such facilities “degrades” the group’s abilities and inspiration for foreign attacks.

Al-Mayadin has become a refuge for ISIS leaders as the group has come under increasing attack in Mosul in Iraq and their de facto capital Raqqa. Some Syria watchers said the group’s media operations have moved to Al-Mayadin as the U.S.-led coalition and allied Syrian Kurdish-led forces close in on Raqqa.

The Associated Press contributed reporting to this story.