According to wikipedia

In its first year of operation, the school had an enrollment of 14 students, with the capacity to accommodate 45 students

So...

At least 600 deaths (they actually got 751 hits with radar) for 99 years is an average of > 6/year. If we assume maximum capacity at all times that's a death rate of about 15% of students per year. That's the low end estimate. If its really 7.5 deaths per year with an average of 30 students per year that's a 25% death rate each year.

Sounds like a Satanic ritual sacrifice center to me. Every few weeks another classmate died. Those kids knew they were going to die.

People don't die and go to Hell.

Earth IS Hell.

Maybe we are the dead.