Drew Barrymore's half-sister found dead

Drew Barrymore was the half-sister of the late Jessica Barrymore, found dead Thursday morning. (AP Photo)

SAN DIEGO, Calif. (ABC NEWS/KGTV) - Drew Barrymore's half-sister has died.

Jessica Barrymore - who, like the actress, was the daughter of actor John Barrymore - would have turned 48 on Thursday.

"Although I only met her briefly, I wish her and her loved ones as much peace as possible," Drew Barrymore told ABC News in a statement. "I'm so incredibly sorry for their loss."

Barrymore, 47 was discovered early Tuesday in a car when a woman leaving for work found a car blocking her driveway, according to the local ABC affiliate KGTV.

According to the San Diego County Medical Examiner's Office, shortly after she was discovered in the car, the fire department confirmed that she was dead.

A cause of death has not yet been determined.