Rwandan genocide
After they got to the school, the Tutsis had no food.  The school's water was also cut off, so the Tutsis would be too weak to fight back.  The Tutsis were still able to fight back for a few days, using stones.  However, on April 21, the school was attacked by the Interahamwe.  They killed about 45,000 Tutsis at the school.  The other 20,000 Tutsis ran to a nearby church to hide, but the militia found them there and killed almost all of them.