(CNN)They wore body armor. They carried assault rifles. And one had declared loyalty to ISIS.
A day after police killed two gunmen who tried to ambush a Garland, Texas, event featuring controversial cartoons of the Muslim Prophet Mohammed, details began to emerge about the shooters.
One suspect, identified as Elton Simpson by a federal law enforcement source, linked himself to ISIS in a tweet posted just before the attack.
He also was no stranger to federal investigators. In 2011, he was convicted of making a false statement involving international and domestic terrorism.
The other suspect, identified as Nadir Soofi by two federal law enforcement officials, was Simpson's roommate in a Phoenix apartment.
He wasn't well-known to federal law enforcement and was not on the FBI's radar, one of the officials said. Investigators were combing through evidence retrieved from the shooters' Arizona home to help piece together a timeline of how their plot came together, the official said.
Authorities are still trying to determine the suspects' motives, U.S. Secretary of Homeland Security Jeh Johnson said Monday. At this point, he said, one thing appears clear: A quick-thinking police officer "likely saved a number of innocent lives."
Simpson and Soofi never made it inside the Curtis Culwell Center in Garland, where in addition to the cartoon contest, a right-wing Dutch politician who's on an al Qaeda hit list was speaking Sunday evening.
A traffic officer working after-hours as security for the event and armed only with a service pistol killed both men, who were wearing body armor and carrying assault rifles, Garland Police Department spokesman Joe Harn told reporters Monday.
"We think their strategy was to get into the event center, and they were not able to get past our perimeter that we had set up," Harn said.
In addition to the officer, who used a .45 caliber Glock, four SWAT team members with high-powered rifles also fired at the suspects, according to a source familiar with the officers involved in the shooting.
"They faced death head-on and, with incredible skill and bravery, were able to save a lot of people," said Zach Horn, an attorney for the officers.
An unarmed security officer working with the patrol officer was shot in the ankle, police said. None of the approximately 200 people attending the event was hurt.
Harn declined to call the incident a terror attack, saying the motive was still under investigation.
"We don't know their intent, other than that they were willing to pull up and shoot police," Harn said.