Police stand near terrorists' vehicle in Texas
Police stand near terrorists' vehicle in TexasReuters

Despite a claim of responsibility by the Islamic State (ISIS) for Sunday's shooting attack in a Dallas suburb, the White House said Tuesday it was “too soon” to tell if the jihadist group was indeed responsible, reports AFP.

Two gunmen shot a security guard in a Dallas suburb before being killed by a police officer outside an event showcasing cartoons of the Prophet Mohammed, which many Muslims find offensive.

One of the two gunmen was later revealed to have tweeted allegiance to ISIS. 

But White House spokesman Josh Earnest told reporters that 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 ISIS.

"So it's too early to say at this point," he stressed.

The ISIS claim marked the first time the extremist group, which has captured swathes 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 had said.

Earnest, however, said ISIS jihadists and other extremists are often "trying to capitalize on the opportunity that's presented by social media to try to communicate with individuals around the world, including inside the United States."

The two suspected jihadists were Elton Simpson, 31, and Nadir Soofi, 34, who shared an apartment in Phoenix, Arizona.

A Twitter account suspected of being linked to the gunmen vowed allegiance to ISIS group, Abu Bakr al-Baghdadi, the New York Times reported. But the IS released no "martyr" video and authorities had yet to find evidence of a direct connection to the jihadists.