One of the two men killed while trying to shoot up a Garland, Texas, event featuring controversial cartoons of the Muslim Prophet Mohammed linked himself to ISIS in a tweet posted just before the attack.

The man, identified by a federal law enforcement source as Elton Simpson, apparently posted a tweet before the attack that read, in part, "May Allah accept us as mujahideen."

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.