The ISIL terrorist group has claimed responsibility for theshooting incident outside a contest for physical depictions of the Prophet Muhammad (PBUH) in Garland, Texas.
The Takfiri terrorist group announced on Tuesdaythat it had conducted the shooting on Sunday night.
"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 group said.
"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," it added.
The attack was the first terrorist act conducted by ISIL in the United States.
Two gunmen opened fire outside a building where an anti-Islamic group, American Freedom Defense Initiative, was staging the provocative contest that would award $10,000 for the top depiction of the Prophet (PBUH).
A security guard was shot in the lower leg during the shooting. The two gunmen were then shot and killed by authorities.
The Sunday event featured extremist Dutch politician Geert Wilders, who is notorious for his anti-Muslim speeches, as its key speaker.
US police have identified the two suspects as Elton Simpson, 31, and Nadir Soofi, 34, who lived in a shared apartment in Phoenix, Arizona.
Simpson had been previously investigated on suspicion of terrorism offenses, a senior FBI official told US media.
He had allegedly planned to travel to Somalia in order to wage a war, according to records.
Following the incident, the Council on American-Islamic Relations (CAIR)condemned theattack "on an anti-Islam event in Garland, Texas, without reservation."
"We also reiterate our view that violence in response to anti-Islam programs like the one in Garland is more insulting to our faith than any cartoon, however defamatory. Bigoted speech can never be an excuse for violence," the CAIR said in a statement on Monday.