Naya Rivera's 'Glee' co-star Heather Morris is offering a foot search and rescue mission for the missing actress

• The Ventura County Sheriff's Office is continuing to search for "Glee" actress Naya Rivera, who investigators say likely drowned in a California lake on Wednesday.
• Heather Morris, who was Rivera's "Glee" co-star, told authorities early Sunday that she wants to assist in the search.
• Rivera rented a boat Wednesday afternoon at Lake Piru in Ventura County — a lake that's known by locals to be a dangerously deep body of water with heavy whirlpools.
• Rivera's 4-year-old son, Josey Hollis, was found sleeping alone on the boat in the lake later on Wednesday.

As of Sunday, officials are continuing to search for missing "Glee" actress Naya Rivera.

According to investigators and the Ventura County Sheriff's Office, Rivera rented a boat Wednesday afternoon at Lake Piru, located in Los Padres National Forest in Ventura County, California. Rivera was with her 4-year-old son, Josey Hollis, who was found in the boat asleep and wearing a life jacket later on Wednesday.

"Investigators believe Rivera drowned in what appears to be a tragic accident," the Ventura County Sheriff's Office said in a statement published Wednesday.

Rivera is best known for playing Santana Lopez in the musical-comedy TV series "Glee," which aired on Fox for six seasons between 2009 and 2015.

On the show, Rivera's character, Santana, married the character Brittany Pierce, played by actress Heather Morris.

Morris, as well as other former "Glee" stars, have shared messages on social media in light of Rivera's disappearance. On Sunday, Morris — a close friend of Rivera — tweeted publicly to the Ventura County Sheriff's Office, saying that she wants to assist in the search.

"My name is Heather Morris, I'm Naya's close friend and co-worker, and I'm trying to conduct an on foot search and rescue mission along with a small group of friends at Lake Piru. I understand your team is doing EVERYTHING in their power, but we are feeling helpless, powerless, and want to help in any way," Morris wrote in a series of tweets.

Lake Piru is known to have dangerous whirlpools, and between 1994 and 2000, seven people drowned there

The lake where Rivera went missing is long-known by Ventura County locals as being a deep body of water that can be dangerous. A Change.org petition, which appears to have been published in response to Rivera's disappearance, is pushing for the installation of signs around the lake that will warn people of its whirlpools.

"Naya Rivera is not the first, nor the last to go missing at Lake Piru. Lake Piru is a very deep lake with very bad whirlpools, people have been asking for years for the city to put up warning signs for swimmers. Locals of Ventura County don't go to Lake Piru for this reason," reads the Change.org petition description. "Tourists have no idea what they're getting into. Lake Piru needs signs."

Between 1994 and 2000, seven people drowned in the lake, which is 130 feet (40 meters) deep, reported the Los Angeles Times.

On Sunday afternoon, the Ventura County Sheriff's Office shared an update on Twitter, saying that "boat crews continue to scan the lake."

The sheriff's office also advised caution to people who intend to search for Rivera on their own.

• Read more:
• Investigators say 'Glee' actress Naya Rivera likely drowned in a California lake in what appears to be a 'tragic accident'
• 25,000 people call for signs warning of dangerous whirlpools at the lake where Glee star Naya Rivera went missing
• 'Glee' stars are sharing heartfelt messages for Naya Rivera after the actress goes missing