Police in Madison, Wisconsin, are trying to determine what prompted a 15-year-old student to open fire at a private Christian school. The shooting Monday was just days before the winter break. A fellow student and a teacher were killed. The shooter also died.

Here are some things to know about the shooting:

Gunfire erupted late Monday morning at Abundant Life Christian School in Wisconsin’s capital city. Police said Tuesday that a second grade teacher called 911 to report the shooting. Authorities had earlier reported that the caller was a student.