Tonight that is what likely brought down metrojet flight 9268, killing all 224 people onboard. The timer set for just enough time to blow the plane up soon after takeoff. We are also learning tonight that officials believe the bomb was a military grade explosive, specifically a plastic explosive like c4. Officials believe an insider with access to the airport planted the bomb. Egyptian Officials Say they interviewed everyone with access to the plane including caterers. Our chief National Security correspondent is out front to begin our coverage tonight what more are you learning about the type of bomb they think was used to bring this flight down . U. S. Intelligence is basically building a more detailed working theory here. Without the forensic evidence they normally have with an investigation like this, access to the wreckage, to the bodies, u. S. Intelligence officials more convinced it was a bomb that took this plane down. It was likely snuck onboard by someone with access to the p