Sydney Aiello—who survived the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, that left 17 dead—took her own life on Sunday afternoon, authorities confirmed.

“Sydney spent 19 years writing her story as a beloved daughter, sister and friend to many,” her family wrote. “She lit up every room she entered. Sydney aspired to work in the medical field helping others in need.”

Aiello’s death was ruled a suicide by the Broward Medical Examiner’s Office, a spokesperson told The Daily Beast.

“The investigation is ongoing,” a Coconut Creek police spokesperson said, confirming authorities received a call about Aiello around 3:23 p.m. Sunday.

Describing her as a “vibrant young woman who was focused on her grades and a joy to be around,” Aiello’s mother, Cara Aiello, told CBS Miami that her daughter struggled with survivor’s guilt after the Parkland shooting and was recently diagnosed with post-traumatic stress disorder.

Sydney Aiello was close friends with Meadow Pollack, one of the 17 people killed at the school on Feb. 14, 2018, when accused shooter Nikolas Cruz opened fire with an AR-15-style rifle. Cruz, 19, is currently being held in Broward County jail.

“It’s terrible what happened. Meadow and Sydney were friends for a long, long time,” Meadow’s father, Andrew Pollack, told the Miami Herald on Friday, adding that his “heart goes out to those poor, poor parents.”

“Killing yourself is not the answer,” he added. “If anyone feels like that they have no one that can understand their pain, if there’s any student out there that’s having a hard time, please reach out to me on Twitter. I understand you. You aren’t alone.”

Sydney’s mother told CBS Miami that her daughter had been enrolled in college classes, but was struggling to attend because she was so afraid of entering a classroom.

“Beautiful Sydney with such a bright future was taken from us way too soon. My friend’s sister and someone dear to Meadow,” Hunter Pollack, Meadow’s brother, tweeted Wednesday, pointing users to a fundraising campaign set up by Aiello’s family to help cover her funeral costs.

On the GoFundMe page, the teenager was described as someone who “filled her days cheerleading, doing yoga, and brightening up the days of others.”

Ryan Petty, whose daughter Alaina died in the Parkland shooting, told CBS Miami that his advice to parents is to “ask questions, don’t wait.” He added that he is worried that more Parkland survivors are still struggling in the aftermath of the massacre.

“It breaks my heart that we’ve lost yet another student from Stoneman Douglas,” Petty said. “My advice to parents is to ask questions, don’t wait.”

If you or a loved one are struggling with suicidal thoughts, please reach out to the National Suicide Prevention Lifeline at 1-800-273-TALK (8255).