Skye McCole Bartusiak, best known for roles in "The Patriot" and "Don't Say a Word," was found dead in her Houston home on Saturday. She was 21.

The cause of death is still unknown. Her mother, Helen McCole Bartusiak, told CNN that Bartusiak had recently suffered from epileptic seizures, and her mother said she believed Bartusiak "had a seizure and choked and nobody was there."

Bartusiak's boyfriend found her sitting up in her bed, her mother said.

Bartusiak's career began at age 6, when she had a small role in "The Cider House Rules" in 1999. She also appeared in "The Patriot" as Mel Gibson's youngest child, and in 2001's "Don't Say a Word." Her latest role was 2012's "Sick Boy."

Abigail Breslin tweeted Sunday that she was "devastated" by Bartusiak's death. "One of my very good friends and someone who was like a sister to me, Skye McCole Bartusiak passed away today. So devastated."