The youngster was found asleep in the boat wearing a life jacket by a passerby Wednesday, but there was no sign of Rivera.
The actress is the mother of a four-year-old son, Josey Hollis Dorsey. While there are reports the child found is her son, authorities have not identified the little boy by name.
CNN has reached out to reps for Rivera for comment.
Officials resumed their search Thursday morning and the Ventura County Sheriff’s Office tweeted concerning the status of the investigation.
“The search for Naya Rivera will continue this morning at Lake Piru,” a tweet from work read. “The lake will be closed to the public while search operations continue. Dive teams from throughout the region will be assisting us through mutual aid.”
Officials never have seen any such thing suspicious and are “reviewing this as a tragic accident,” said Ventura County Sheriff’s Deputy Chris Dyer in a press conference Thursday morning.
“We hope for the best, we prepare for the worst,” Dyer said.
Rivera shot to fame playing Santana Lopez on the hit Fox series “Glee.”
Several celebs including “Glee” cast members Harry Schum, Jr. and Iqbal Theba tweeted their concern.
“Oh God… mercy… please…,” wrote Theba, who played Principal Figgins on the show, in a tweet sharing a news story about Rivera’s disappearance.
Heather Morris, who played Rivera’s bff and love interest on the show, Brittany Pierce, posted concerning the actress on her behalf Instagram stories.
“We need all the prayers we can get to bring our Naya back home to us,” Morris wrote. “We need your love and light.”
Singer and actress Demi Lovato, played Dani, another of Santana’s girlfriends on the show.
Lovato posted on her behalf Instagram stories asking visitors to “Please pray for @nayarivera to be found safe and sound.”