HOUSTON, Texas (KTRK) -- The Federal Bureau of Investigation's Houston Field Office told ABC13 that four juveniles have been arrested in recent days due to threats made to area schools.

"We always see an uptick in threats of mass violence targeting schools at the beginning of the school year," Special Agent in Charge Jason Hudson said.

The FBI said three arrests were made in connection to threats against Pasadena ISD schools, and one was made in connection to a threat made to Huntsville High School.