Authorities say they have arrested a 26-year-old man in a series of threatening phone calls that shut down Southern California schools and hospitals last week.
Officials from the FBI, Los Angeles County Sheriff's Department and other agencies announced the arrest at a joint news conference Tuesday.
Sheriff's Capt. Mike Parker says 26-year-old Gerardo Cortez was arrested and his home in Monrovia was being searched. Parker says Cortez has a previous arrest on a similar allegation.
Parker says investigators used advanced technology that he could not discuss further to identify Cortez.
Last week, schools in the San Gabriel Valley east of Los Angeles including Arcadia High School were shut down after hoax calls reporting campus gunmen.
Authorities say a similar call to police Monday resulted in brief lockdowns at four hospitals.