Former Glee actress Naya Rivera is feared dead after going missing at a lake in Southern California.

A search operation was launched after her four-year-old son was reportedly found alone on a rented boat at Lake Piru, the Ventura County Sheriff’s Department said.

Police found Rivera's life vest on the boat and believe that 'she did go in the lake' to go swimming, acknowledging that 'this may well be a case of drowning'.

According to local reports, Nivera rented a boat at Lake Piru at about 1pm local time.

The alarm was raised and a search operation launched using helicopters, drones and dive teams, police said.

On Tuesday, Rivera tweeted a picture of her and the boy together, which was captioned: “Just the two of us.”

Rivera, 33, is best known for playing Santana Lopez in the musical comedy series Glee.

She earned significant success starring as high school cheerleader Santana and the California-born star followed it up with her feature film debut in 2014 horror film At The Devil’s Door.

She later had a role in the Lifetime TV series Devious Maids.

Rivera was engaged to the rapper Big Sean in October 2013 but they ended their relationship in April 2014.

She then began dating actor Ryan Dorsey and they got married in Mexico in July that year.

The couple welcomed their first child, Josey Hollis, in September 2015. Rivera filed for a divorce after two years of marriage but later called off the separation.

The couple finalised their divorce in June 2018.

After news she was missing broke, Rivera’s former Glee co-star Harry Shum Jr tweeted: “Praying.”