Son wants to go on independent study. He will be home with grandma who has severe Alzheimer's

and older brother who is her caregiver while I work. Yesterday my son, 17 HS senior, saw a man on campus with what appeared to be a gun. He reported it to the office. Moments later 2 other students who do not know my son, reported the same thing. The school was locked down for 2 hours (3pm to 5pm) The police found a man, a janitor at the school, and brought him in the office where my son and the other students were and asked them in front of the man "Is this the guy you saw?" They were scared but confirmed they thought it might be the guy. The police never found a gun. The automated phone system called the families and said the claim of a man with a gun on campus was "completely unfounded." During the lockdown the police and school officals questioned my son and he felt they were implying he and the other students were "making it up." He is now afraid to go back to school because he is sure it was a gun and is afraid he will be the first victim when this guy snaps. My son does know what guns look like, we have several and go target shooting as a family.