Chicago Fire has avoided the cancellation axe that took down other top TV shows,

including Blue Bloods and Young Sheldon — but sources exclusively tell

Life & Style it’s set to torch some of its leading actors. Fan favorite Eamonn Walker, 61,

who has portrayed Battalion Chief Wallace Boden since the show’s 2012 debut and has appeared in 250 episodes, is being smoked after the current season.

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Walker’s departure comes on the heels of the announcement that longtime cast member Kara Killmer, who plays paramedic Sylvie Brett, will also leave the show.

A source says it’s just business as usual now as TV mega-producer Dick Wolf, the creator of all three One Chicago series, has already booted big names Sam Waterston and Camryn Manheim from Law & Order.

“None of Dick’s nine shows has been outright canceled, but pretty much all of them have let some of their mainstay actors go to control costs — especially after the actors’ and writers’ strikes cost them hundreds of millions of dollars,” says a source. “It makes good business sense, since shows like Chicago Fire are expensive to produce.”

Adds the insider, “But Eamonn’s character was so beloved that fans of the show are certainly going to miss him — and the remaining cast members are looking over their shoulders to see who’s next!”