Congratulations, Daniela Ruah! It's a girl!

NCIS: Los Angeles' Ruah and husband David Olsen welcomed their second child on Sunday - a little baby girl by the name of Sierra Esther.

"Apparently, she thought Labor Day weekend meant LABOR day weekend," Ruah joked as she shared Sierra's first photo. "Look who showed up 3 weeks early!"

Married in 2014, Ruah and Olsen are also the proud parents of River, 2. The youngster appears beside his baby sis in the hospital, quickly adapting to his new role as a big brother.

 
Although Sierra was in breach, Ruah had the opportunity to follow through with a safe, natural birth. All went well, and within 24 hours the little family was back at home.

"[Sierra] entered the world in her own way- breeched!" the actress explained. "I was a good candidate to deliver her naturally so I needed to find a doctor in LA who would know how to do it. Fortunately I found one of the few... Healthy & happy mommy & baby walked out of the hospital 24hrs later."

Not only does Sierra have a built-in playmate thanks to River, she will also get to hang with her newborn cousin, Esme. Serving as both Ruah's NCIS: LA costar and brother-in-law, Eric Christian Olsen also welcomed a baby girl this summer with his wife Sarah Wright. Barely a month older than Sierra, Esme will grow up alongside her little cousin just as her older brother, 2-year-old Wyatt, is growing up with River.

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