Authorities believe she may have drowned, her son is unharmed.

Actress Naya Rivera, known for role on the hit TV show “Glee,” is missing after authorities found her 4-year-old son drifting alone on a boat at Lake Piru in California. Authorities believe she may have drowned.

Rivera and her son came to the lake around 1 p.m. local time to rent a boat and were seen going out on the lake together in the early afternoon, Eric Buschow, captain at the Ventura County Sheriff’s Office, told ABC News.

However, three hours after they left the dock, another boat saw the child who appeared to be alone on board. The boy was found asleep and the boat notified authorities.

The child told officials that he had been swimming with his mother and that he got back in boat but his mother did not.

A dive and aerial rescue operation began immediately, but the Venture County Sheriff’s Office said it has suspended the search for Rivera, 33, overnight. The search for Rivera will resume at first light.

Rivera’s vehicle was found parked on the ramp near the lake and her purse was found on the boat. Lake Piru is located about 56 miles north of Los Angeles.

ABC News’ Lauren Botchman and Will Ganss contributed to this report.