Authorities have issued an updated statement on former “Glee” star Naya Rivera, who went missing and is being searched for at a Southern California lake.

On Thursday afternoon, the Ventura County Sheriff’s Department confirmed they have not found her but believe “Rivera drowned in what appears to be a tragic accident.“

They added that around 100 personnel are actively looking for her, including divers and the use of sonar equipment.

Late on Wednesday investigators confirmed that Rivera, 33, was the person being searched for in the waters of Lake Piru, which is approximately 56 miles (90 kilometres) northwest of downtown Los Angeles.

KNBC reported late Wednesday that Rivera rented a pontoon boat at the Lake Piru reservoir Wednesday and that her young son was found on the boat wearing a life vest. Rivera’s identification was found on the boat where her son was asleep. He “told investigators that he and his mother had been swimming in the lake, and he got back in the boat, but Rivera did not.” Sheriff’s officials launched a boat and helicopter search Wednesday afternoon, but that had been suspended by nighttime.

“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,” Captain Eric Buschow said during a news conference.

In an update Thursday morning, the Sheriff’s Department said that they would be continuing the search, with the lake closed to the public and dive teams assisting.

As of Thursday afternoon, CBS Los Angeles is reporting that authorities are now calling it a search and “recovery” operation.

Rivera’s 4-year-old son Josey is from a marriage with actor Ryan Dorsey. The couple finalized their divorce in June 2018 after nearly four years of marriage.

She called her young son “my greatest success, and I will never do any better than him” in her 2016 memoir Sorry Not Sorry.

Rivera last posted on Twitter on Tuesday:

The actress was engaged to rapper Big Sean in 2013, but their relationship ended a year later. The pair met on Twitter and collaborated musically, with the rapper appearing on Rivera’s debut single “Sorry”.

Rivera played Santana, a cheerleader in the musical-comedy “Glee” that aired on Fox from 2009 until 2015. She 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.

Celebrities responded to the news on Twitter. See some of the reaction below.