Three students dressed in black trench coats, carrying gas masks and guns on their way to a costume party at their high school drew a large police response.

Several people called Coquitlam RCMP on Wednesday afternoon to report the men were heading toward Arch Bishop Carney Secondary School.

“Local police responded quickly, contacting school administration and calling in the Lower Mainland District Emergency Response Team to lock down (the school),” RCMP Const. Sharen Leung said Thursday.

The school principal told police the three were participating in an event that allowed students to wear costumes to school. They had been counselled on what were appropriate costumes but ignored school policies.

The students were questioned and had parts of their costumes confiscated. While they were not charged, the school is expected to take disciplinary action.