Smoking hot reveal alert: This article discusses the series finale of ABC's "Station 19," now streaming on Hulu.

There has never been a wildfire like the one burning out of control in Thursday's "Station 19." series finale.

The havoc from the Seattle-based spinoff of Shonda Rhimes' "Grey's Anatomy" is so powerful that it spreads to the series' mothership. In the ultimate crossover, the overwhelmed staff of Grey + Sloan Memorial Hospital treat the injured in the "Grey's" Season 20 finale, which aired just ahead of "19."

The deadly blaze, which began in the May 23 episode, imperils the "Station 19" firefighting team fans have come to love over seven seasons and threatens to spread across Seattle. There's a gnarly fire tornado, firefighters are forced to take drastic tarp shelter from all-consuming flames and the birth of a baby in a car amid the mayhem.

"We wanted to use every last cent," says executive producer and writer Zoanne Clack of the finale blowout. Yet as each character faces death, the finale also flashes forward to a bright future: Everyone survives the carnage and has their own happy ending.

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"We were going for satisfying," says Clack. "We used the flash-forwards to show what they are living and fighting for while they're in peril. What's going to give them the drive to keep going and not just give up?"

Clack and executive producer Peter Paige touched on the still-burning "Station 19" hotspots.

Were there 'Station 19' crossovers with 'Grey's Anatomy'?

The action in the finale moved quickly to Grey Sloan, where injured firefighter Theo Ruiz (Carlos Miranda) is rushed in on a gurney headed for emergency surgery. Ruiz's operating-room ordeal is a major subplot of the "Grey's" season finale. But there are many crises at the hospital, including Captain Andy Herrera (Jaina Lee Ortiz), who recovers from her brush with death surrounded by friends and colleagues.

"We came out of the mothership and we returned," says Paige. "We love those connections and interactions within the universe. This was an opportunity to do that one last time."

What happened to Ben Warren in the 'Station 19' finale?

Ben Warren (Jason George) has been a surgical resident at Grey Sloan starting in Seasons 6, before becoming a firefighter on the "Station 19" spinoff. The dangerous job was a constant source of concern for his wife, "Grey's Anatomy" surgeon Miranda Bailey (Chandra Wilson).

As Warren watches Ruiz wheeled into surgery, it's clear that he misses the profession. But he runs out to save lives and deliver the healthy baby with OB/GYN Carina DeLuca (Stefania Spampinato). Three months later, Warren tells Herrera that he is leaving Station 19 to return to medicine.

"He knew he couldn't be as great a firefighter because his body was giving out," says Clack. "It was a natural progression for Ben to move back into medicine." The career change also busts the door wide open to his likely return to "Grey's" next season.

Warren's flash-forward shows him watching his grown children's graduations with Bailey. The final scene shows Pruitt Arike Miller, whom the couple raised after her firefighter father, Dean Miller (Okieriete Onaodowan), died in Season 5. Pruitt graduates from the firefighter academy.

"For Pruitt to go into firefighting was kind of bittersweet, because now they have to do that all over again with a worry," says Clack.

What happened to Andy Herrera in the finale?

Herrera rallies her team: When forced to take cover from the fire, Herrera puts herself at risk to slip away and seek vital help. Even after she recovers, Herrera has burns on her neck as she receives the greatest compliment from the departing Warren — that her father, the legendary Captain Pruitt Herrera (Miguel Sandoval), who died in Season 3, would be wildly proud of her.

With a worthy promotion, Chief Herrera gets the series' final words, speaking to a new group of Station 19 cadets.

"We wanted the last moments to show that the show might be over, but the spirit and energy of Station 19 doesn't have to stop," says Paige. "We left those words to Andy to carry forward. We knew that's where the show needed to end."

Herrera is seen exiting the station to a bright, sunny future.

Travis Montgomery and Vic Hughes are 'Station 19' BFF's

In a finale update we have to mention the best friend and fan-favorite couple Travis Montgomery (Jay Hayden) and Victoria Hughes (Barrett Doss). When Hughes sets off from Station 19 to head to a job in Washington, D.C., her bestie and clever-banter buddy Travis shows up at the airport to join her.

"It turns out my life is where you are," Montgomery tells her.

"Rom-com is a part of the Shondaland vocabulary. But what if the great rom-com of this finale is actually these two best friends choosing each other. That felt so right," says Paige. "They got the platon-com ending. That friendship is every bit as valuable as the show's other great loves."