(WJW/AP) – “Smash” actress Megan Hilty is speaking out after her sister, brother-in-law and nephew were recently killed in a plane crash.

In an Instagram post, she confirmed that her family members were on board the small floatplane that crashed Sunday afternoon into Puget Sound off the coast of Whidbey Island, Wash.

“My beloved sister Lauren, brother-in-law Ross and baby nephew Remy were on that plane,” Hilty said in the post.

The actress said her sister was eight months pregnant and expecting a baby boy at the time.

“The last three days have been the worst of our lives,” the post went on to say. “There are truly no words to appropriately convey the depth of our grief.” 

Ten people were killed in the crash.

The U.S. Coast Guard released the names of the victims early Tuesday. The body of one of the dead was recovered after the crash, but the other nine remain missing despite an extensive search.

The Northwest Seaplanes flight was on its way from Friday Harbor, a popular tourist destination in the San Juan Islands, to a Seattle suburb when it went down without sending out a distress call. The cause of the crash was not immediately known, but the Federal Aviation Administration earlier this year issued a safety directive for the type of aircraft involved.

The dead include pilot Jason Winters, activist Sandy Williams, winemaker Ross Andrew Mickel, his pregnant wife Lauren Hilty and their child Remy Mickel. Also killed were passengers Joanne Mera, Patricia Hicks, Luke Ludwig, Rebecca Ludwig and Gabrielle Hanna.

“Lauren and Ross left behind my niece who we are all holding in our hearts. Thankfully, she was not on the plane,” Hilty said in the post.

The actress went on to say that the continued love and support has meant so much to their family.

“It has been so comforting to know just how loved Lauren, Ross, Remy and Luca truly are.”

Hilty rose to fame in Broadway, playing Glinda in “Wicked.” She also starred as Ivy Lynn in the musical drama TV series “Smash.”

The Associated Press contributed to this report.