Divers recovered items during their search of Seccombe Lake, FBI spokeswoman Laura Eimiller said.
While she confirmed that the lake's search is over, she declined to comment on whether the retrieved items are related to the mass shooting that left 14 people dead.
"I'd caution you that divers generally pull all sorts of items out of a public lake," she told CNN.
The search began on Thursday after authorities learned the shooters, Syed Rizwan Farook, and Tashfeen Malik, may have been in the area the day of the attack, said David Bowdich, chief of the FBI's Los Angeles office.
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They are seeking the electronic trail of the killers, whom they interacted with, how they hatched and carried out the plot, and why.
One of the items divers were likely looking for was a missing hard drive from the couple's computer. Investigators believe the hard drive was removed as a way to cover up the crime. The couple died in a shootout with law enforcement hours later, leaving behind a 6-month-old daughter.
So far, Islamic State has noted the husband-and-wife team publicly only as "supporters". Malik went on Facebook at the time of the attack to swear the couple's allegiance to the terror group.
Farook's longtime friend and relative-through-marriage, Enrique Marquez, bought the assault rifles used in the shooting more than three years ago, about the time he converted to Islam, San Bernardino Sun quoted a law enforcement official as saying.
Marquez, who checked himself into a Long Beach mental hospital after the attack, told investigators that he and Farook were plotting an attack in 2012.
Idaho Senator Jim Risch, a Republican who sits on the Senate Select Committee on Intelligence, said they had an actual plan, including buying weapons, but became apprehensive and shelved it because of law enforcement activity and arrests in the area.
Marquez has not been charged with a crime and has been cooperating with authorities.