Kyle Bangayan, 24, of Pomona was booked into the downtown jail Sunday for investigation of making criminal threats, police Cmdr. Andrew Smith said. He remained in jail with bail set at $500,000.
Police detectives and FBI agents went to the east Hollywood home of Bangayan's father after a resident notified authorities about the threatening Facebook postings that referred to the deadly school shootings in Connecticut, Smith said.
"When we get information like this, we take it very seriously, even more so now in light of the Connecticut school shootings," Smith said.
On Friday, Adam Lanza, 20, shot and killed 20 children and six adults before killing himself at Sandy Hook Elementary in Newtown, Conn.
The names of the Los Angeles schools and details about the threats were not immediately released.
Detectives and the FBI were still investigating.
FBI spokeswoman Laura Eimiller didn't immediately return telephone messages on Monday.
When Los Angeles officers and FBI agents arrived at the suspect's home, the father gave permission for a search, authorities said.
Nine weapons were confiscated, but Smith said details about the firearms and ownership weren't being released.
The home is in a working-class neighborhood about eight miles northwest of downtown Los Angeles. Pomona is about 30 miles to the east.