The following reveals major plot points from tonight’s NBC’s One Chicago crossover. NBC’s Chicago Med, Chicago Fire and Chicago P.D. came together for an epic crossover event taking the franchise to the next level.

After five years, the One Chicago franchise finally has another three-part crossover event airing tonight, and the bosses previewed what’s in store. Beginning with Chicago Fire at 8 p.m. ET, the event’s official logline reads,

It's been five years since the last three-part Chicago Fire, Med, and P.D. crossover. This one did not disappoint.

There's an explosion near a government building, which causes the ensemble casts of all three One Chicago shows to arrive on the scene. There are injured and trapped victims all a