TEMPO.CO, Cairo - The Islamic State group claimed responsibility on Tuesday for a weekend attack at a center near Dallas, Texas, that was exhibiting cartoon depictions of the Prophet Muhammad — though it offered no evidence of a direct link to the attackers.

An audio statement on the extremist group's Al Bayan radio station said that "two soldiers of the caliphate" carried out Sunday's attack in Garland and promised the group would deliver more attacks in the future.

The Islamic State did not provide details and it was unclear whether the group was opportunistically claiming the attack. It was the first time the extremists, who frequently call for attacks against the West, claimed responsibility for one in the United States.

It was also unclear from the statement whether the group, which holds a third of Syria and Iraq, had an actual hand in the operation, or whether the two suspects had pledged allegiance to the group and then carried it out on their own.

The statement was read on Al Bayan radio — a station based in the Syrian city of Raqqa, which the group has proclaimed the capital of its self-data-styled caliphate.

"We tell ... America that what is coming will be more grievous and more bitter and you will see from the soldiers of the caliphate what will harm you, God willing," it said.

Two suspects in the attack were shot dead after opening fire at a security guard outside the center. Officials identified them as Elton Simpson and Nadir Soofi.

According to mainstream Islamic tradition, any physical depiction of the Prophet Muhammad or other prophets is considered blasphemous. Drawings similar to those featured at the Texas event have sparked violence around the world.

There have been numerous attack in Western countries believed related in some way to the group. In October, Canada was hit by two terror attacks by so-called "lone wolves" believed to have been inspired by the Islamic State group.

AP