A 16-year-old living in the country illegally was indicted for allegedly bringing a loaded gun and knife to Smithtown High School West, according to Suffolk County District Attorney Ray Tierney.

Prosecutors say the teen was indicted Tuesday on weapons charges, and that they are a Colombian national living in Nesconset.

The firearm, which was reported stolen, was confiscated from their backpack after numerous students alerted school officials to a concerning social media post showing the firearm off, prosecutors said.

Tierney said that on Oct. 26, the teen was being interviewed by the school's principal about an earlier incident involving another student when the principal learned the student had allegedly posted a photo of himself holding a gun on social media.

The principal then searched the teen’s backpack and allegedly recovered a small kitchen knife with a cover, an extended magazine with five rounds inside and a Kahr P380 caliber handgun.

The student was arrested at the scene and faces charges of criminal possession of a weapon, criminal possession of a weapon on school grounds and criminal possession of stolen property.

The teen is being held on $50,000 cash, $100,000 bond or $500,000 partially secured bond.

The United States Immigration and Customs Enforcement lodged a detainer and says it plans to take custody of the student following the prosecution.