[s3e19] I Am The Apocalypse Here

In the wake of the trauma, Dawson and Casey share a romantic reconciliation at Molly’s, though the stability of their relationship remains a lingering question.

Severide survives his surgeries but is shaken by the near-death experience.

This episode introduced the core cast that would eventually lead Chicago Med :

Chicago Fire Season 3 Episode 19 Review: I Am ... - TV Fanatic

Lieutenant Kelly Severide is critically injured in the blast while trying to stop the attacker. He spends much of the hour in surgery, experiencing visions of his late friend Shay while Dr. Hannah Tramble (Laurie Holden) fights to save him. Major Introductions & Arcs

Hospital administrator Sharon Goodwin (S. Epatha Merkerson) places the facility under immediate quarantine, trapping members of 51 inside with a potential biohazard and an active electrical fire in the ceiling.