(NBC) – It’s a big night for NBC’s “Chicago Fire,” the show that gave rise to the “Chicago Universe” on Wednesdays, celebrates its 200th episode tonight and there may be more than just a numerical milestone that makes the episode memorable.

Filming the “Chicago Fire” pilot almost 10 years ago was a thrill for Jesse Spencer who plays Matthew Casey on the show.

“I remember being excited, riding around on fire trucks. And kids like, waving at us,” said Spencer.

But childhood wish-fulfillment gave way to very grown-up stories reflecting the daily work and camaraderie of first responders.

 “They do and they see, what nobody should ever have to see,” said David Eigenberg, Christopher Herrmann on the series, about the first responders they portray.

“We all still feel it’s an honor to represent these men and women,” added Eamonn Walker who takes on the role of Wallace Boden.

An honor celebrated recently during the production of tonight’s milestone episode.

“We have fun, and I think that translates through the screen, and I think people like to be a part of, you know, that energy,” said Taylor Kinney who stars as Kelly Severide.

“We’re a show that lifts each other up and I think that’s what keeps everybody tuning in every week,” said Executive Producer Derek Haas.

Fans tuning in tonight will apparently see an addition to the firehouse family.

“The show leans on the idea of family and community. And that is 100 percent what we are on this set,” said Joe Minoso, who has played Joe Cruz from the show’s very beginning.

But the firehouse may also say a farewell. At the end of last week’s episode and promos airing this week tease what appears to be Matthew Casey’s departure.

And while Spencer’s tight-lipped about his future, tonight’s milestone does have him reflecting on the past decade.

“It’s just been an iconic time. It’s been a wild ride. and I’ve loved every minute of it,” he said.

So have fans of “Chicago Fire.”

“Chicago Fire” airs tonight at 8 p.m., right after “Chicago Med” and just before “Chicago P.D.”

And “Law and Order: SVU” also has an upcoming milestone, its 500th episode will air Thursday night.