(CNN) Sydney Aiello, who survived the 2018 massacre at Marjory Stoneman Douglas High School in Florida, has died from suicide, people close to the family told CNN.

Her mother, Cara, told CNN affiliate WFOR that Aiello suffered from survivor's guilt after one of the deadliest mass shootings in modern US history and had recently been diagnosed with post-traumatic stress disorder.

Aiello, a student at Florida Atlantic University, died Sunday. Her funeral was Friday in Davie, Florida.

Aiello had been on campus the day of the mass attack but was not in the building where the shootings took place, her mother said, according to WFOR. Aiello, a cheerleader in high school, graduated just months after a troubled teen gunned down 14 students and three teachers there.

The family of Parkland school shooting victim Meadow Pollack described Aiello as "someone dear to Meadow."

Marjory Stoneman Douglas High School this week sent an email of bereavement about Aiello's death to staff, a teacher told CNN.

A former history teacher described Aiello as "nice and always smiling and talkative."

"She was always eager to say hello to everyone in the hallway," the teacher said.

The February 14, 2018 massacre was carried out by former Stoneman Douglas student Nikolas Cruz, then 19, who confessed to being the gunman and was indicted on 17 counts of murder.

In the weeks after the carnage, grieving students launched a nationwide movement calling for public policy changes that would prevent a similar tragedy.