Michelle Trachtenberg, the actor known for “Gossip Girl,” “Buffy the Vampire Slayer” and “Harriet the Spy” died Wednesday. She was 39. New York City police responding to a call at a residential high-rise building in Manhattan found Trachtenberg unresponsive and emergency medical services pronounced her dead at the scene,

The cause of death for actress Michelle Trachtenberg has been ruled “undetermined” by the New York City Medical Examiner, according to an agency spokesperson.

Michelle Trachtenberg's cause of death was revealed Thursday after the 39-year-old actress was found dead in New York City Wednesday morning.

The cause and manner of Michelle Trachtenberg’s death are undetermined, according to the New York City Office of the Chief Medical Examiner.

Blake Lively on Wednesday shared a lengthy tribute to her “Gossip Girl” costar Michelle Trachtenberg, who was found dead in her New York City apartment on Wednesday morning. Trachtenberg, also known for her roles in “Buffy the Vampire Slayer” and “Harriet the Spy,

Rosie O’Donnell paid tribute to her former co-star, Michelle Trachtenberg, who was found deadin her New York City apartment on Wednesday. “Heartbreaking,” O’Donnell said in a statement to Us Weekly. “I loved her very much.

Michelle Trachtenberg's cause of death was ruled "undetermined" by the Office of Chief Medical Examiner in New York City, Fox News Digital confirmed.

Sarah Michelle Gellar, Taylor Momsen and Blake Lively are among those paying tribute to Michelle Trachtenberg, who died Wednesday.

While there is no criminality suspected, the city Medical Examiner couldn’t tell what caused the star’s death from a preliminary exam.

Gellar is honoring her late 'Buffy the Vampire Slayer' costar, who died on Wednesday, February 26, with a powerful quote from the show.

Sarah Michelle Gellar has paid tribute to her former Buffy The Vampire Slayer co-star Michelle Trachtenberg following her death Wednesday at 39.