COOPER: New details tonight about the attempted terror attack in Garland, Texas, that ISIS has claimed credit for. The two gunmen, as you know, were shot and killed by police outside of the building where a cartoon contest featuring images of Mohammed were taking place. One of the gunmen, Elton Simpson was on the FBI's radar. Now, CNN has just learned that hours before the attempted attack, the FBI sent a warning to police in Garland. Our justice correspondent Pamela Brown joins me with the latest. So the warning that they sent, what do we know about it?</s>PAMELA BROWN, CNN CORRESPONDENT: What we are learning today, Anderson, from FBI director James Comey is that the FBI sent a bulletin to local authorities in Garland, Texas three hours before Elton Simpson arrived and opened fire and</s>COOPER: There was a heavy police presence there and do we know if any of that was in response to the warning from the FBI?</s>BROWN: What we know is that a few days before the event, Anderson, a bulletin was sent out about the fact that this could inflame extremists living in the U.S. It could upset them, and so they were well aware of the possible threat. So, there was already security in place at that event, and Simpson was just one of many people on the list of possible extremists who may want to target the event. So, what police will tell you is that they already had a plan in place and they were prepared for anything. Anderson.</s>COOPER: All right. Pamela Brown, thank you very much for the reporting on that. Obviously there is still a lot to be learned on the investigation into this, how much ISIS actually did have connections with any of these would-be terrorists. We'll obviously continue to stay on that. That does it for us tonight. Thanks very much for watching. Coming up right now, Mike Rowe's "Somebody's Gotta Do It."</s>COOPER: We'll be back at 11:00 with another edition of "AC 360." I hope you'll join us for that.
FBI Warning Texas Police about Terrorist Gunmen.