A man was arrested after allegedly threatening to commit a mass shooting at a synagogue, police in California said Friday.

Ross Farca, 23, was charged with making criminal threats, possession of an illegal assault rifle and manufacturing an assault rifle, the Concord, Calif. Police Department said in a statement.

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Officers said they were alerted by the FBI to comments in an online chatroom and that they traced them to Farca. They said the comments included threats against Jewish people, threats to shoot law enforcement and claims to possess an assault rifle along with the synagogue threat.

Police said they arrested Farca earlier this month and searched his home, finding an illegal AR-15 semi-automatic rifle and high capacity magazines. They also said they found Nazi literature.

Farca was being held in the Contra Costa County Jail, according to the statement. Detetives also obtained an order preventing Farca from buying firearms, according to the statement.

Farca's arrest follows a separate shooting at a California synagogue earlier this year that killed one person. Eleven people were killed at a synagogue shooting in Pittsburgh last year.