A teen facing felony charges over a school threat in Suffolk County was arraigned Monday.

The 16-year-old from Brentwood appeared at Family Court in Central Islip. He was charged with making a terroristic threat.

The teen allegedly posted the threats on Snapchat over the weekend, including one that said he was going to "shoot up the Brentwood Freshman Center at 9 killing students and teachers. Be ready."

MORE: Police: Teen arrested for making terroristic threat against Brentwood school 

Another post apparently shows the teen holding a gun. A third photo shows guns and ammunition, with the phrase "murder on my mind."

Parents and students reported the posts to police. Suffolk Chief of Department Stuart Cameron says within hours, police tracked down the teen, arrested him and charged him.

The school superintendent issued a statement saying that student safety is of their utmost priority, and that parents are encouraged to speak with their children about the district's code of conduct and the importance of appropriate behavior when using social media.

Police have not released the student's name.