In a May 5, 2015 news bulletin the Islamic State's (ISIS) official radio station, Al-Bayan, which broadcasts in Mosul, claimed responsibility for the May 3 shooting in Garland, Texas. The broadcast stated:
"Two of the Caliphate's soldiers attacked an exhibition in the American [town of] Garland, Texas. This exhibition staged a competition of cartoons that were insulting to the Prophet Muhammad. The brothers opened fire on the exhibition, and as a result one of the police officers in charge of protecting the exhibition was injured. The brothers were killed in the exchange of fire. We pray Allah to accept them in the highest paradise. We say to the protector of the Cross, America, that what is coming will be more bitter and calamitous. The soldiers of the Islamic State will show you what will harm you, Allah willing. Tomorrow draws near."
Source: Archive.org/details/AlbaYan_7, May 5, 2015.