Despite the effort, several social science experts feel the zero tolerance approach adopted in schools has been implemented too harshly, with unintended consequences creating other problems. Despite the safety measures that were implemented in the wake of the tragedy at Columbine, school shootings continued to take place in the United States at an alarming rate. Virginia Tech, Sandy Hook, and Stoneman Douglas were three subsequent school shootings that far surpassed the casualties of the 1999 massacre, subsequently raising concern of gun violence in the United States.