A caller threatened to drop off a bomb at an Orange County mosque and police are trying to figure out if the call is tied to similar crimes in the area.
Detectives came to investigate Tuesday meeting with mosque officials at the DarulFalah Islamic Center behind closed doors. There are no suspects.
The threat comes only weeks after six California mosques received the same hand-written letter claiming that President-elect Trump would "Do to Muslims what Hitler did to the Jews."
The Council on American Islamic Relations says the recent incidents have left their community more than concerned.
"If someone is intent on causing harm, unfortunately all you can do is reduce the chances but you can't prevent that," said Hussam Ayloush, the executive director of CAIR-LA.
In Tustin the mosque director showed cards of support that have arrived from strangers, all wanting to ensure the neighborhood is protected.
There are cameras inside the building and soon there will be more outside.
Muslims say they will remain strong in their faith and hope that something positive comes from the negative threat.