Thousands of children each year are disciplined at school for fighting, making threats, bringing a weapon to school or other “serious” confrontations, reports the State Department of Education.

During the 2010-11 school year, the most recent year for which data is available, 14,049 fights would take place at school; 1,203 students would get into trouble for bringing a weapon to school, and 710 violent crimes would take place.
Think these numbers are bad? It used to be much worse.
Over the last five years, the number of these “serious” incidents taking place on school grounds has decreased from 50,347 to 43,236 — a 14 percent drop.
The number of non-serious offenses where students were still disciplined — for things like school policy violations or petty theft — has dropped from 126,756 to 89,802 incidents — a 29 percent reduction.
For a district-by-district breakdown on prevalence of violent and unsafe behavior, see this link. For a breakdown on the number of school security staff in each district, see this link.