As one other person commented, the number 17 doesn’t necessarily mean the 17th door, the first number may mean a particular building while the second number is a direction. Not all schools use the same method. Also, when you have two buildings on a campus, when schools are involved, all buildings will have lockdown procedures. In my area they are building the middle school, junior high, and high schools on the same campus. They’re going to be numbered differently based on which building it is. Not saying you’re wrong, but I am saying there are legit explanations for that number. The church and the school are on the same campus, they’re both going to have a lockdown procedures that gets implemented in those types of situations.