Local gang members take over Firehouse 51 in the upcoming episode of "Chicago Fire" season 5.

Titled "Telling Her Goodbye," next week's episode will see Firehouse 51 fall under siege when strangers arrive and take over their headquarters. According to the official synopsis, a turf war escalates in the area and puts the crew in danger. Members of 51's truck and squad find themselves caught in the middle and become unsuspecting hostages when a group of armed gang members arrives and assumes control over the establishment. The tense situation takes a turn for the worse when one of the gang members gets wounded and in serious need of medical help.

NBC released a new set of promo images for the upcoming hour and it shows the 51 members bringing the wounded infiltrator inside an ambulance. A distraught elder woman looks on and she appears to be the victim's mother. Other photos from the hour show the entire staff of 51 gathered together in one place, with most of them looking worried and afraid.

In the previous episode titled "Deathtrap," 51 responded to an out of control warehouse fire with over a dozen victims still trapped inside. The team had to race against the clock and rescue all of them. It was later revealed that one of the victims who was found in critical condition is Lexi (Alina Jenine Taber), the daughter of "Chicago P.D." character Alvin Olinsky (guest star Elias Koteas).

51 teamed up with "Chicago P.D.'s" Hank Voight (guest star Jason Beghe) to find new leads on the incident and they eventually discovered that the fire was intentionally set. The episode also saw Severide (Taylor Kinney) attempt to reconnect with Anna (Charlotte Sullivan).

Meanwhile, a new face is expected to be introduced in the show. Kamal Angelo Bolden was recently tapped to join the cast as a new firefighter and he will appear in the current season's remaining four to five episodes.

The fifth season of "Chicago Fire" airs every Tuesday night at 10 p.m. EST on NBC.