WASHINGTON - US investigators probed the background of two slain gunmen Tuesday after the Islamic State group claimed it had ordered an attack targeting an exhibit of caricatures of the Prophet Mohammed.
The White House said it was too soon to tell if the jihadist group was behind the failed attack, in which two gunmen were shot dead by a police officer before they could storm the event.
The case "is still under investigation by the FBI and other members of the intelligence community" to determine if the two assailants had any ties to the IS group, White House spokesman Josh Earnest told reporters.
"So it's too early to say at this point."
The Islamic State claim marked the first time the extremist group, which has captured swaths of territory in Syria and Iraq using brutal methods, alleged to have carried out an attack in the United States.
"Two of the soldiers of the caliphate executed an attack on an art exhibit in Garland, Texas, and this exhibit was portraying negative pictures of the Prophet Mohammed," the jihadist group said.
But Earnest said IS jihadists and other extremists are often "trying to capitalise on the opportunity that's presented by social media to try to communicate with individuals around the world, including inside the United States."
US Senator John McCain, who is often critical of White House security policy and has warned of the jihadist threat, also cautioned that the claim should not be taken at face value.
"There's no doubt that these young people were most likely inspired by ISIS," he told reporters, adding: "... there's a difference between carrying out an ISIS order and being inspired by ISIS."
Police said the two gunmen drove up to the conference centre Sunday in Garland, where the American Freedom Defence Initiative was organising a controversial Mohammed cartoon contest, and opened fire with assault rifles, hitting a security guard in the ankle.
A Garland police officer then shot and killed both men with his service pistol.
The two suspected jihadists were Elton Simpson, 31, and Nadir Soofi, 34, who shared an apartment in Phoenix, Arizona.