Officials are searching for actress Naya Rivera after her 4-year-old son was found alone on a boat she rented Wednesday afternoon, officials said.

Rivera rented the boat about 1 p.m. and had an afternoon of swimming with her son, who was the last to see her before she went missing, said Ventura County Sheriff's Department Capt. Eric Buschow.

Buschow said the boy got back onto the boat after a swim but his mother did not follow. “We’re going on the belief that she did go in the water and we have not been able to locate her. So this may well be a case of drowning,” Buschow told reporters.

The 4-year-old was found sleeping on the boat by himself by other boaters in the lake.

"He's in good health," Bushow said of Rivera's son. The boy was initially reported by authorities to be a 3-year-old girl. "The family is going through a very traumatic time right now."

The search for the 33-year-old "Glee" actress is continuing and will draw more resources Thursday morning.

Buschow said the Ventura County Sheriff's Department will be joined by search and rescue teams from neighboring counties and will deploy divers and air units in the morning. Officials were able to confirm her identity because they found her wallet and identification on the boat, Bushow said.

Rivera played Santana, a cheerleader in the musical-comedy “Glee” that aired on Fox from 2009 until 2015. Rivera appeared in 113 episodes of the series and dated co-star Mark Salling, who killed himself in 2018 after pleading guilty to child pornography charges.

Includes information from the Associated Press.