“I wish I could have helped,” O’Donnell said of Trachtenberg, who died at 39 years old

Rosie O’Donnell is mourning the loss of her Harriet the Spy costar Michelle Trachtenberg.

Following the news of Trachtenberg’s death at age 39 on Wednesday, Feb. 26, O’Donnell said in a statement that hearing what happened was “heartbreaking.”

“I loved her very much. She struggled the last few years. I wish I could have helped,” she added.

O’Donnell, 62, starred alongside Trachtenberg in 1996’s Harriet the Spy, which was released when Trachtenberg was just 10 years old and marked her big-screen acting debut.

Another cast mate, J. Smith-Cameron spoke out in a statement on Feb. 26. “I played Mrs. Welch, Harriet’s mother in Harriet the Spy. Michelle had been on a Nickelodeon show called Adventures of Pete & Pete but this seemed to be her first lead film role. She was so excited,” she recalled.

“Her natural ebullient nature was ratcheted up into giddiness as she tried to learn how to handle all that came with that. She was a very charming little girl,” the actress continued. “Years later we found each other on social media and connected briefly. She was always very warm toward me. I feel very shocked and unsettled to hear of her passing.”

07/29/96 Rosie O”Donell and Michelle Trachtenberg star in the first Nickolodeon movie “Harriet the Spy”
Michelle Trachtenberg and Rosie O’Donnell in Harriet the Spy (1996). Getty
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The New York Police Department confirmed to PEOPLE on Wednesday that officials responded to a 911 call at 1 Columbus Place in New York City around 8 a.m.

Michelle Trachtenberg attends Cadillac Celebrates the 92nd Annual Academy Awards at Chateau Marmont on February 06, 2020 in Los Angeles, California; ROSIE O’DONNELL ON WHO WANTS TO BE A MILLIONAIRE
Michelle Trachtenberg in Los Angeles on Feb. 6, 2020; Rosie O’Donnell. JC Olivera/WireImage; Christopher Willard/Disney via Getty
“Upon arrival, officers observed a 39-year-old female unconscious and unresponsive. EMS responded to the location and pronounced the victim deceased,” police said, adding, “Criminality is not suspected.”

The investigation remains ongoing. The New York Post was first to report on her death.

Michelle Trachtenberg arrives at the Alice + Olivia presentation during Mercedes-Benz Fashion Week Fall 2015 on February 16, 2015 in New York City.