Jordan Harper (Writer of The Great Red Dragon) said that they are going to explain in episode 6x08 how the bombing happened.

What if Thomas McAllister and Gale Bertram worked together in the garden house room. Bertram first glanced to Thomas when he lowered his sleeve to show his shoulder. Thomas planted the bomb somehow.

Maybe they have figured out that Thomas planted the bomb in the room and that he is escaping in the park, still alive.

What if both Blake Association members Thomas McAllister and Gale Bertram are escaping and Red John is somewhere else?