'NCIS: LA' Stars Credit the Fans for Helping Them Reach 300th Episode Milestone (Exclusive)

LL Cool J, Chris O'Donnell, Daniela Ruah and more talk to ET about Sunday's landmark hour.

NCIS: Los Angeles turns 300 this Sunday -- 300 episodes, that is!

The long-running CBS procedural, a spinoff of the NCIS mothership, celebrates TV's rare milestone with its upcoming episode, which sees the team investigating a fatal explosion at a military base, Callen (Chris O'Donnell) taking the next step with Anna (Bar Paly) and Sam (LL Cool J) moving in with his father, Raymond (guest star Richard Gant).

"It was just amazing to have gotten there," showrunner R. Scott Gemmill told ET on the PaleyFest carpet in April. "The first time you hit a hundred you feel so fortunate, then two hundred and three hundred is unheard of. For us, we just made it a celebration of our family and that’s called working family because that’s what we do. We've all been together 13 seasons some of us and it really is. We see the cast or crew get married, have children, so it’s a celebration of life for us and we're so happy that we get to do it year after year and we're blessed, that’s for sure."

The stars of the series also looked back on 13 seasons (and counting) and expressed gratitude for having the chance to reach this point.

"It could've been three and out. It could’ve been three episodes, so it's one of those things where you can't really expect it to happen," LL Cool J told ET of the accomplishment. "I'm just glad it did. Fans giving us love and we're just having fun doing what we do."

"It's so far beyond anything I ever imagined -- even my most ambitious hopes for the show," O'Donnell said. "Three hundred is a magical number and it was amazing that everyone stuck together. It's a group of people who really enjoy working together and feel blessed to have this job and love the show so much, so we stay at it."

They credited the viewers for keeping with the show since the very beginning.

"They're the reason why we're on the air as long as we've been on the air and I love it," O'Donnell explained. "We're coming up on 300 episodes on the show and you lose track of what's going on but the fans, they know exactly what's going on and they correct us sometimes on things, so it's nice to be able to celebrate a bit." 

Added LL Cool J of the fan support: "It's excellent it feels great, grateful. "We havin' a lot of fun. When we first started, I figured it'd be a couple years. I had no idea we'd be going into a 14th season, so it feels good."

For Daniela Ruah, she said it's "surreal" being part of a show that is able to reach such rarefied air.

"On one hand, 300 episodes means that the 299 before that were filled with camaraderie and building together and becoming such a brotherly-sisterly family, and 300 on [the other] hand is another episode where we get to have fun and be with people that we love. But the concept of 300 just makes it a whole other [level]," she said. "We're just so lucky 'cause you can work as hard as you want, but there are things that are just simply out of your control and CBS deciding to keep us on for this long is not in our control as a cast. We can behave, we can do our best, we can hope that the fans enjoy us, but we're all blessed, put it that way. Very, very blessed to have come this far."

NCIS: LA airs Sundays at 9 p.m. ET/PT on CBS.

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