Jessica Barrymore, a half sister of actress-producer Drew Barrymore, was found dead early Tuesday in a car in National City, California, near San Diego.

San Diego ABC affiliate KGTV said Tuesday that resident Marta Lopez was leaving for work around 6 a.m. and found her driveway blocked by a car. She found an unresponsive woman inside with an energy drink between her legs and white pills scattered about.

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Firefighters called to the scene found the woman dead, said the San Diego medical examiner's office. No cause of death has been determined, pending an autopsy.

"Although I only met her briefly, I wish her and her loved ones as much peace as possible, and I'm so incredibly sorry for their loss," Drew Barrymore, 39, said in a statement Wednesday.

Jessica Barrymore, who KGTV said was a well-liked employee at a Petco pet-supply store, was the daughter of the late John Drew Barrymore, a troubled, failed actor who was also Drew Barrymore's father. The two women had different mothers. Jessica Barrymore would have been 48 Thursday, the TV station said.