A Stall High School student was arrested Wednesday on a drug charge after a search for a gun that was rumored to be at the school turned up empty, authorities said.

The tip came from a Royal Canadian Mounted Police liaison in Washington, D.C., according to an incident report. The liaison called Charleston County dispatch about “social media threats that were intercepted,” the report stated.

A student, identified in a police report as 17-year-old Shermaine Whitley, posted a tweet threatening to bring the gun to school, according to investigators.

Police officers searched Whitley, but no weapon was found, investigators said.

Officials did, however, find drugs on Whitley, North Charleston police said. He was charged with possession of marijuana.

Whitley told police he and another student had not been getting along and so the messages “were just threats to scare the other student,” the report stated. He also told investigators he didn’t have a gun and never has had a gun, according to the report.

Stall High School was placed on lockdown while authorities investigated the incident.