A search operation was launched after her four-year-old son was reportedly found alone on a rented boat at Lake Piru.
The search will resume “at first light” on Thursday, the sheriff’s department said.
Rivera, 33, is best known for playing Santana Lopez on the musical comedy series.
According to local reports quoting the sheriff’s department, Nivera rented a boat at Lake Piru at about 1pm local time. Rivera and her son were swimming, and he was wearing a life vest, but she was not.
The alarm was raised and a search operation launched using helicopters, drones and dive teams, police said.
Naya welcomed son, Josey Hollis, with then-husband Ryan Dorsey in 2015.
On Tuesday, Rivera tweeted a picture of her and the boy together, which was captioned: “Just the two of us.”
More to follow.