Skye McCole Bartusiak, an actress best known for her role as Mel Gibson’s daughter in the 2000 movie, The Patriot, died Saturday at the age of 21.

“We lost our girl,” Skye’s mother, Helen McCole Bartusiak, told CNN on Sunday.

The cause of death is unknown at this time, but Skye’s mother said that epileptic seizures had plagued her daughter for most of her life and had returned in the past week.

According to CNN, Skye’s boyfriend found the young actress sitting up in her bed in the garage apartment adjacent to her parents’ Houston home.

“We think she had a seizure and choked and nobody was there,” said the heartbroken mother of the actress.

Helen reportedly started cardiopulmonary resuscitation on her daughter before paramedics arrived. “They were working on her for 45 minutes and could not get a heartbeat,” she said. “I’ve done CPR on that kid more than one time, and it just didn’t work this time.”

Actress Skye McCole Bartusiak, who played a daughter in "The Patriot," has died. She was 21. http://t.co/pcZg40KhZF pic.twitter.com/GRTNPsRz3m

— CNN Breaking News (@cnnbrk) July 20, 2014

Skye began her film career as a 6-year-old in 1999’s The Cider House Rules. She followed that role with others, including 2001’s Don’t Say a Word, opposite Michael Douglas. In 2012, she starred in the thriller, Sick Boy. Bartusiak’s television credits include playing a young Kate Austen on Lost and starring in a lengthy arc on 24.

“The girl has lived such an amazing life,” Helen said. “She was a kind and really beautiful girl.”

Skye had been preparing to produce and direct her first feature film in recent months, her mother said.

Image via Wikimedia Commons