According to SITE, a company that monitors jihadi groups, ISIS claimed responsibility for the attack in the latest edition of its al-Bayan news bulletin. The group identified the two suspects as "two soldiers from the soldiers of the Caliphate."
The Associated Press reports that the Sunni extremist group goes on to warn the United States that more attacks are coming. The wire service adds:
"The statement did not provide details and it was unclear whether the group was opportunistically claiming the attack as its own. It was the first time the Islamic State, which frequently calls for attacks against the West, had claimed responsibility for one in the United States."
Police say two men who have been named as Elton Simpson and Nadir Soofi came out of a car firing assault rifles at the Garland event on Sunday.
One officer fired back and killed the men. As we reported, Simpson had been in trouble with the law in the past. In 2011, he was convicted of lying to the FBI, which was investigating whether he had planned a trip to fight in Somalia.
"U.S. authorities have said they are investigating whether Sunday's shooting has any link to international terrorism. But there are clues that one of the gunmen was an ISIS sympathizer.
"Moments before the attack, Simpson posted an ominous tweet with the hashtag #texasattack: 'May Allah accept us as mujahideen.' The tweet also said he and his fellow attacker had pledged allegiance to 'Amirul Mu'mineen,' which means 'the leader of the faithful.' CNN terrorism analyst Paul Cruickshank said that likely refers to ISIS leader Abu Bakr al Baghdadi.
"And earlier, Simpson had asked his readers on Twitter to follow an ISIS propagandist. After the shooting, the propagandist tweeted: 'Allahu Akbar!!!! 2 of our brothers just opened fire.'"