Two men were arrested Thursday night, one at LAX and one in Orange County, by a Joint Terrorism Task Force, the FBI said.
While the sources would not elaborate on specifics, they said the case involved suspects who are trying to travel abroad to join ISIS. The men were expected to be charged Friday.
The unarmed suspects fit a pattern of individuals who had been recruited by ISIS as foreign fighters, particularly through social media propaganda, sources told NBC News.
The task force includes agents from the FBI, Anaheim police and the Orange County Sheriff's Department.
The men were identified Friday as Muhanad Badawi, 24, and Nader Elhuzayel, 24, both from Anaheim, according to U.S. attorney's office spokesman Thom Mrozek.
One was arrested at an Inn in the city, she said Friday, FBI spokeswoman Laura Eimiller said.
The FBI has served at least two search warrants in connection with the case, according to NBC News.
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Law enforcement sources told NBC News that there was no local public safety threat.
Ryan Bougard and Asher Klein contributed to this report.