The two men who opened fire at a “Draw Muhammad” event Sunday night in Garland, Texas, were identified as roommates from Arizona, including one who had been on the FBI’s radar, ABC News and Phoenix media outlets reported Monday morning. The shooting injured a security guard in the parking lot where the event was held. Elton Simpson was identified as one of the shooters; he and the second gunman were shot and killed by authorities.

Simpson, of Phoenix, was previously convicted of lying to the FBI about plans to go to Africa, but a judge determined there was not enough evidence to suggest he was planning to join up with a terror group as the bureau claimed, ABC News reported. The Arizona man was believed to have used the Twitter hashtag #TexasAttack about 30 minutes before the shooting erupted outside the community center. Dallas investigators will reportedly name the second suspect when they give an update on the Garland shooting at an unspecified time, tweeted Chris Williams, a reporter with KPNX-TV, Phoenix's NBC affiliate.

The “Draw Muhammad” contest was billed as a free speech event where attendees could draw the Islamic figure, with $12,500 going to the winner, identified by the Daily Beast as Albanian-American cartoonist Bosch Fawstin. Pamela Geller, president of the American Freedom Defense Initiative, organized the event at the Curtis Culwell Center in Garland, a suburb of Dallas.

The drawing of Muhammad is a contentious issue and is seen as insulting to Muslims. Hard-line Muslims have sometimes reacted violently to the depictions of the prophet. Cartoons of Muhammad published by the French magazine Charlie Hebdo led to the terror attack on its Paris offices in January, resulting in the deaths of 12 people, including 10 journalists.

Simpson and the second man were roommates at a Phoenix apartment complex, the FBI told KPNX. An ID on one of the gunmen and the registration of the car they used led investigators to hone in on Arizona for their search. A SWAT team entered their apartment around 3 a.m. local time Monday, said Katie Conner, a reporter with KNVX-TV, Phoenix’s ABC affiliate.

A robot was believed to have been sent into the apartment after FBI investigators and a bomb squad arrived there, ABC News reported.