Islamic State Claims Responsibility for Texas Attack on 'Draw Muhammad' Event

The Islamic State (IS) today claimed it was behind Sunday's failed attack on the "Muhammad Art Exhibit and Contest" in Garland, Texas. This has yet to be independently verified — and no further evidence has been offered for the claim — but this is the first time the group has claimed responsibility for a planned attack in the US.

A news bulletin on IS's al Bayan Radio described the two men who attempted to storm the event as "soldiers of the caliphate," and said the exhibition in the conference center in suburban Dallas had been "portraying negative pictures of the Prophet Muhammad."

"We tell America that what is coming will be even bigger and more bitter, and that you will see the soldiers of the Islamic State do terrible things," the statement continued.

Elton Simpson, 30, and Nadir Soofi, 34, were shot dead at the scene after they opened fire on the Curtis Culwell Center and wounded a security guard. The identities of the two men were made public on Monday.

Related: Two gunmen killed in Texas "draw Muhammad" contest attack. Read more here.

The attackers — who died wearing body armor — both resided in the Autumn Ridge Apartments in north Phoenix, Arizona.

Simpson had been under surveillance since 2006, according to court documents. In 2011, he was convicted of lying to the FBI during a terrorism investigation and was sentenced to three years of probation. The Twitter account thought to belong to him provides evidence that he was in contact with some well-known IS members, and also included a pledge of allegiance to "the leader of the faithful" — believed to refer to IS leader Abu Bakr al Baghdadi. It has since been suspended.

Soofi, meanwhile, was a father who once owned a pizza and hot-wings restaurant called Cleopatra. His mother told the Dallas Morning News that she was grappling to understand how he could have done this and left his 8-year-old son behind. "He was raised in a normal American fashion," she said. "Yes, he was very politically involved with the Middle East. Just aware of what's going on. I don't know if something snapped or if Elton Simpson was just working on him."

The shootout occurred as Sunday's event — which offered a $10,000 prize for the best caricature of the prophet — was drawing to a close. About 40 extra police officers had been sent on the day to provide additional security, at a further cost to the organizers of $10,000.

After the two men were killed, guests were evacuated. The conference center was then searched for any explosive devices.

Security guard Bruce Joiner, who was shot in the ankle, has since been released from hospital.

Related: "We'll die before they make us leave": Lebanese Christians are ready to face the Islamic State on Syria's border. Read more here.

Follow Sally Hayden on Twitter: @sallyhayd