It was the culmination of three months worth of planning by Isabella County Emergency Management giving first responders and teachers as close a look at the real thing as they could.
The mock shooting took place at Shepherd High School this morning.
The scenario included a shooter entering the school and killing about a dozen acting victims and holding several teachers and students in their classrooms during the lock down.
Police and paramedics responded going through their training and dealt with the shooter and his victims.
Police say a real life drill like this is invaluable especially when they are allowed to take advantage of one of their local schools.
9&10 News' Eric Lloyd and photojournalist Jacob Johnson were there for the exercise this morning and have more details.