Widebody; Low Wing; 2 Turbojet Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 200; Flight Crew Total 12202; Flight Crew Type 1899
Situational Awareness; Communication Breakdown
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Security
General Police / Security Involved
Human Factors; Procedure
At TOD we received ACARS from Ops asking if we had sent a message about an emergency. We checked with the Flight Attendants (FAs) and they said all was normal; so we used ACARS to let Ops know we had no emergency. After landing we discovered we had to wait for a gate and the passengers had to wait for Customs and Border Patrol before deplaning. I called dispatch on SAT phone and zone on my cell phone. Neither of them knew of any issues other than ZZZ Center had been closed earlier and was causing delays. I relayed that information to the passengers and thanked them for their patience. After crossing 28R on the north side; we noticed a CBT and an airport vehicle who followed us to the gate. Eventually we got to [the] gate and door 1L was opened. We kept the seatbelt sign on and the door closed. We heard shouting and when we turned on the flight deck door access camera; we saw individual FAs and passengers being escorted off with their hands up. There were about 15-20 officers on the airplane with automatic weapons drawn. There were also officers standing behind concrete pillars on the ground with weapons drawn. An FBI agent came to the door eventually and she explained a call had been made to someone who said there were armed individuals on the plane who were going to take over. We expressed our dismay that we had no notification of an issue. Obviously; we should have been notified of the threat; and we would have followed appropriate procedures for a Level 4 threat. As we exited the passengers were still assembled in the concourse waiting to retrieve their bags. They and their children were obviously upset; but grateful they were OK.
[Report narrative contained no additional information.]
Air carrier Captain reported being left out of critical communication from ground security forces.