All schools in the vast Los Angeles Unified School District have been ordered closed on Tuesday due to a threat.

A bomb threat was sent by email but authorities have not yet said whom the threats were sent to or who they were against. The threat was called a rare threat and all the schools have been shut down as of Tuesday morning.

Los Angeles police have notified the FBI and they are also on the case. Authorities have stated that they are taking this credible threat every seriously and they have begun searches throughout the district. Since the district is so large, they have shut down the schools for the remainder of the day and tomorrow until pending circumstances.

The threat comes less than two weeks after two shooters killed 14 people in San Bernardino, California.