Actress Naya Rivera is missing and presumed dead in a Southern California lake, according to authorities, after officials found her 4-year-old son floating alone on their rented boat on Wednesday afternoon.

The Ventura County Sheriff’s Office confirmed late Wednesday that a “possible drowning victim” at Lake Piru was Rivera, 33, best known for her breakout role in the TV series “Glee.”

Officer Chris Dyer confirmed at a news conference that the initiative had gone from being a search-and-rescue mission to a search-and-recovery effort. He said the office is presuming Rivera drowned in the lake.

“There’s no signs of foul play, no signs of anything that went wrong besides a tragic accident,” Dyer added. “Switching that mode to a search-and-recovery mode, like I said, does not change the efforts and does not change the gusto, what we push forward with the search operation. The goal is still to bring Ms. Rivera home to her family, so they can have some closure.”

The search on Thursday concluded without any sign of Rivera. Recovery efforts are expected to resume Friday at daybreak. Max O’Brien, a volunteer diver with the Ventura County Sheriff’s Office Underwater Search and Rescue Team, told reporters that the volume of debris in the lake is so dense that that divers have only one to two feet of visibility in some areas. The divers are searching for Rivera mostly through touch, with O’Brien calling the effort a “Braille search.”

Rivera rented a pontoon boat with her child, Josey Hollis Dorsey, about 1 p.m. Wednesday on Lake Piru, a reservoir in Los Padres National Forest, according to security footage released by authorities. About three hours later, when the boat was past its scheduled return time, another boater on the lake found Josey sleeping alone on the pontoon. Dive teams, helicopters and drones were deployed as part of the search-and-rescue mission that night.

Josey, who officials said was unharmed, told investigators he and his mother were swimming but she never got back to the boat. Josey was found wearing a life vest, and investigators located an adult life vest on the pontoon, sheriff’s office spokesman Eric Buschow said Wednesday. The child, whose father is actor Ryan Dorsey, was reunited with family members, police said. Rivera and Dorsey, who divorced in 2018, share custody.

Ventura County Sgt. Kevin Donoghue announced in a second news conference Thursday afternoon that there was “no indication, after talking to her son, that Ms. Rivera made it to shore, so the focus of our search efforts are in the water at this time."

Donoghue said “technology like sonar” is being implemented to locate Rivera, as well as manpower that includes “over 100 personnel that are on-site, actively searching. The assets that we currently have in place looking for her include helicopters from both the sheriff’s office and from the U.S. Coast Guard; we have about a half a dozen boats out on the water; we have some personal water craft out on the water; multiple dive teams. We’re searching the northern half of the lake, which is a good size area, hoping to find any clues or evidence of her disappearance.”

Rivera’s acting career began when she was 4 on the CBS sitcom “The Royal Family.” Throughout her career, the Los Angeles native made guest appearances on shows such as “The Fresh Prince of Bel-Air,” “Family Matters” and “The Bernie Mac Show.”

She won critical acclaim in the role of cheerleader Santana Lopez on Fox’s “Glee,” appearing as a main character for the majority of the show’s six-season run. She was nominated for a Grammy in 2011 as part of the “Glee” ensemble cast for their rendition of Journey’s “Don’t Stop Believin’.” While on the show, Rivera signed a record deal with Columbia Records in 2011, one of the first “Glee” actors to ink a solo artist contract. In 2016, she published the memoir “Sorry Not Sorry.”

She most recently had a recurring role on the YouTube Premium show “Step Up.”

On social media, fans, friends and colleagues offered support for Rivera and her family. Heather Morris, a former co-star of Rivera’s on “Glee,” told E! News that she was having a difficult time wrapping her head around the news of her friend.

“I’m holding on to hope that the rescuers will bring Naya home in a swift and speedy recovery,” Morris said in a statement. “I know she would remind me in moments like this that God has a plan for everything and although we may not know what that plan is, we need to keep our chin up and stay strong.”

Jackée Harry, who starred alongside Rivera on “The Royal Family,” said she was praying for her former co-star.

“Please God, don’t cut this life short,” she tweeted.

In the days leading to Wednesday’s boating trip, Rivera shared photos of her and Josey, as well as inspirational messages about enjoying life.

“No matter the year, circumstance, or strifes everyday you’re alive is a blessing,” she tweeted. “Make the most of today and every day you are given. tomorrow is not promised.”