If it actually is the foyer, then the possibility of a terrorist attack increases. I was under the impression initially that this was nearer the stage.
We observers should let the police, medics, and others do their jobs and after the smoke clears, we can figure out what actually happened.
Yes. Evidently some folks leaving early were met by officers who told them to exit another way. As they turned to go that way, the officer said, “RUN”, and then the explosion went off.