'NCIS: LA' Stars Reflect on 'Emotional' Final Day on Set, Promise 'Beautiful Ending' to Series (Exclusive)

LL Cool J, Chris O'Donnell, Eric Christian Olsen, Daniela Ruah and more talk to ET about wrapping up the show after 14 seasons.

Emotions were running high for the cast on the final day of filming on NCIS: LAThe stars of the outgoing CBS procedural officially wrapped production Wednesday, and they reflected on what it was like saying goodbye to the show, their characters and each other after 14 seasons.

"The 14-year thing, we say it, it doesn't seem real because it feels like we just started this and saying goodbye, it's emotional. It was more emotional than I anticipated when we shut it down two nights ago," NCIS LA star Chris O'Donnell told ET on the red carpet for the series wrap party Friday. "They said, 'It's a series wrap on Chris.' I couldn't -- I had trouble speaking to our crew. You want to be eloquent and say something great. But the fact is, there was so much emotion, so much love for the people in the room. It was an amazing run. I'm just so grateful. So grateful for the opportunity and the success and the fans tuning in and for the friends that I made along the way."

"There were a lot of emotions. People were definitely feeling it," co-star LL Cool J said of their "bittersweet" last day, likening it to a "graduation" of sorts. "At the same time, there was a lot of gratitude. Because we know that we put a lot of work in. We know that we put together a body of work, a body of art that people can watch and enjoy for many, many years to come." He said reaching that last day felt like a culmination of his "full, complete contribution" to the show.

"At some point, you have to go if you want to level up, if you want to do something different, if you want to move into different stages in your life," the actor-rapper noted. "There's a certain level of melancholy because... you're not going to be working with them closely on a daily basis. But it's for the greater good. I believe the best is yet to come."

For co-star Eric Christian Olsen, the tears were flowing on that final day as well. "I cried," he admitted, sharing that he ended up giving "an impromptu speech." "What I said, which is the fulfillment of dreams and that the reason that we chose this business was to come out here and tell stories and we got to do that. We got to tell 324 stories. My parents call it 'coming home on Sundays,' like 'Eric's coming home on Sundays,' and they get to watch it for an hour. It comes in waves of gratitude and sadness and celebration."

Co-star Daniela Ruah shared insights into the speech LL Cool J gave to the cast and crew when he wrapped, promising that connection is life-long. "LL gave a great speech when he wrapped. He was like, 'Look, just because this is over doesn't mean we're not friends. It doesn't mean that we don't talk to each other anymore. It doesn't mean if you don't have an idea to come to me with the idea,'" the actress revealed. "It's like that bond from 14 years. You can't just end because you hear the word, 'That's a wrap.'"

Added cast member Medalion Rahimi, who plays NCIS Special Agent Fatima Namazi, "Emotions were running very high [on the final day]. I cried, I think, five times... But it was fun and exciting because it was like the 'last day of school'-type of vibe, but also it was heavy at the same time. It was a lot but it was great."

Of course, the cast took key keepsakes from set to serve as invaluable memories from their time on NCIS: LA. LL Cool J revealed he took several of Sam Hanna's bulletproof vests and items from the boat shed, while Olsen rocked one of his character's jackets on the carpet for the wrap party, and got his hands on a set of dumbbells. O'Donnell, meanwhile, shared he took some pieces of clothing and his chair, while co-star Caleb Castille, who portrays NCIS Special Agent Devin Roundtree, kept all his character's chair backs and Ruah has some of Kensi's signature outfits and badge in her closet.

As for what fans can expect from the series finale, which will air May 21, the cast promises surprises and a satisfying ending.

"I think the writers did a very good job of wrapping this show up," Gerald McRaney, aka Kilbride, said of the series' final episode. "They've always been good but a lot of the shows that I've seen here lately, when they come to an end, they just stop. This one has an ending and it has a beautiful ending."

"There's so much that we reveal," Castille teased, adding "our fans can expect the usual recipe with a little bit extra sprinkled in." He said viewers will be "very satisfied" with how everything wraps up. "I am satisfied as well. I'm very grateful that our writers and our producers, within the time that they had to write all of this and squeeze it in and get everything wrapped up, they completely crushed it."

Rahimi hinted that the series finale serves as a finite end to the story, even though there may be one or two small loose threads. "I don't think there's any open-ended or untied loose ends. My character's ending is a little open-ended, but I think that gives the audience an opportunity to make up what happens to her," she explained. 

"I think the fans will be pleased," O'Donnell said. "There's some resolution, there's some explanation. There's some answers and some really pleasant surprises. They're in for a treat."

NCIS: LA airs Sundays at 10 p.m ET/PT on CBS.