Drew Barrymore's half-sister Jessica Barrymore was found dead in San Diego, California on Tuesday, according to KGTV ABC10.

Barrymore was reportedly found inside her car around 6 a.m. by local resident Marta Lopez. Lopez noticed that Barrymore's car was blocking her driveway and she approached the vehicle, only to find Barrymore unresponsive.

Dozens of white pills were reportedly found inside Barrymore's car, though National City police say the cause of death is still unknown.

"Her car was parked right here last night around midnight," onlooker Oscar Sandoval told the news. "I thought she was sleeping or waiting for someone."

Barrymore would have turned 48 on July 31. Jessica and Drew, 39, share the same father, actor John Drew Barrymore.