Gossip Girl alum Blake Lively has joined in the ongoing tributes for her co-star Michelle Trachtenberg, whose death was confirmed this morning. The actress was found unresponsive in her New York City home and pronounced dead at the age of 39.

Lively posted a lengthy statement to her Instagram Story in remembrance of the actress, who played Georgina Sparks alongside Lively’s Serena van der Woodsen on the late 2000s CW teen soap.

“This is the first day I met Michelle,” Lively captioned a still of them in Gossip Girl. “She was electricity. You knew when she entered a room because the vibration changed. Everything she did, she did 200%. She laughed the fullest at someone’s joke, she faced authority head on when she felt something was wrong, she cared deeply about her work, she was proud to be a part of this community and industry as painful as it could be sometimes, she was fiercely loyal to her friends and brave for those she loved, she was big and bold and distinctly herself.”

Lively’s statement continued, “Time passes. You take for granted that you get the chance to see an old friend. To paraphrase, the real tragedies in life are the ones that blindside you on an idle Tuesday.”

Trachtenberg appeared in 28 episodes of Gossip Girl as a major antagonist. Other cast members such as Ed Westwick, who played Chuck Bass, and Chace Crawford, who played Nate Archibald, have expressed sympathies for the loss.

Trachtenberg’s other big project co-stars such as Kim Cattrall, who worked with the actress on Ice Princess, and various Buffy the Vampire Slayer cast from James Marsters to David Boreanaz also mourned the actress Wednesday. Trachtenberg starred as Buffy’s kid sister Dawn Summers.