A high school in Longueuil was placed under lockdown Monday morning, after someone called 9-1-1 and reported someone with a gun was inside.

The lockdown was lifted about 12:45, nearly three hours after it began.

The Longueuil police tactical squad conducted searches of the Jacques-Rousseau high school on Gentilly St. E.

Longueuil police spokesman Marc David says three teenagers have been arrested.

"We have just proceeded to the arrest of three students of the school," he said. "One of them was in posession of an air pistol."

David says the investigation is still going on and they don't have the ages of the students for the moment. He says they've been taken to the police station to be met by detectives.

At least one student was taken to hospital suffering from shock.

Parents looking for information can call (450) 463-7191.

Photo: Patrick Sanfacon (La Presse)

Photos: Laura Casella (CJAD)