The incident happened the evening of March 29 at Don Knabe Regional Park.
According to the sheriff's department, the toddler's father was pushing a stroller carrying another child. The toddler, who's two and a half years old, was riding his bike in front of him and took off. The father ended up losing sight of him.
Moments later, Preston Hoang and Julian Mata - who were playing and fishing at the time of the incident - spotted the toddler in the lake and quickly called 911.
The sheriff's department said they used flashlights to direct deputies to the area where they saw boy.
"Kudos to Preston and Julian," said Los Angeles County Fire Department Deputy Chief Elenie Pappas during a news conference Thursday. "What an amazing example of two young men, and thank you to their families because they could not have done what they did unless their families taught them how to do it."
When deputies pulled the boy out of the lake, he wasn't breathing and didn't have a pulse, according to authorities. Deputies performed CPR on the toddler and three minutes later, he started breathing again.
"My children ... they're adults, but it does take you back," said LASD Deputy Xavier Alvarez, who was among the deputies recognized for their heroic efforts. "It makes you wonder, 'What if that was my child at that point?' I wanted to do just about everything to save that child.'"
The toddler has since fully recovered.