UPDATED: More than 100 personnel, including divers from several law enforcement agencies, continue to search for former “Glee” star Naya Rivera, who went missing after a boating trip on Lake Piru on Wednesday.

The Ventura County Sheriff’s Office shifted the incident to a search and recovery operation on Thursday morning.

“We are presuming that an accident happened and we are presuming that she drowned in the lake,” Deputy Chris Dyer said at a press conference. “The goal is still to bring Ms. Rivera home to her family so they can have some closure.”

Rivera rented a boat with her 4-year-old son about 1 p.m. on Wednesday. About three hours later, an employee at the boat rental shack noted that the boat was overdue and went to look for her. He found the boat on the north side of the lake. The boy was in the boat, apparently asleep, and Rivera was missing.

Sgt. Kevin Donoghue said Thursday afternoon that the lake is about 30 feet deep in the area where the boat was found, and that the search was complicated by the presence of trees and other debris in the water. Searchers are scouring the northern half of the lake, he said. He said it can often take several days to a week to locate a body.

“We have no indication, after talking to her son, that Ms. Rivera made it to shore,” Donoghue said. “He gave enough information to investigators to conclude that his mother never made it out of the water.”

Investigators recovered surveillance video from the boat dock that showed Rivera and her son getting onto the boat and leaving the dock. There was no video from the north end of the lake. The boy was wearing a life jacket, and another life jacket was found in the boat, Donoghue said. Rivera’s purse and her ID were also found in the boat.

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The search continues for actress Naya Rivera in Lake Piru after she went missing Wednesday, July 8. Michael Buckner/Variety

Searchers from several neighboring counties began to look for Rivera late Wednesday afternoon. The search included helicopters, a drone team, and multiple dive teams. The search was called off about 10 p.m. Wednesday due to dangerous conditions, including varying depths and underwater debris, and it resumed at dawn on Thursday.

Dyer said that visibility in the lake is 8-10 inches during the day. He said that Rivera was familiar with the lake, and had been there before.

He said there was no indication that Rivera was upset or distraught.

“I can’t stress enough that this just seems like a tragic accident — come out here for a great day and something bad happens,” Dyer said.

Rivera is best known for her role as Santana Lopez on the Fox series “Glee,” playing the character from 2009 until 2015. After her breakout role on the musical series, she went on to appear in “Devious Maids” and “Step Up: High Water.” As part of the “Glee” cast, she received several nominations at the Screen Actors Guild Awards, Grammys and Teen Choice Awards. During her “Glee” run, she signed to Columbia Records in 2011 and released a single, titled “Sorry,” with rapper Big Sean.