[1][2][3][4] At approximately 11:00 a.m. Heinz Schmidt entered St. Mary's Catholic School, carrying a briefcase packed with six to ten pistols (whether revolvers or semi-automatics, depending on the source) and about 1000 rounds of ammunition, which he had bought several weeks before the shooting.

Because of the large number of rounds, the owner of the gun shop where Schmidt had bought his arsenal contacted the police, though the incident was not found to be important and not investigated further.

[7] While Miss Pohl fled into a classroom nearby Schmidt entered room 8b, which was occupied by 65 girls, most of them being 6 or 7 years old, and immediately began firing at them.

Schmidt shot the school janitor, Butz, who attempted to apprehend him, hitting him in the face, before going upstairs where he was tackled by teacher Hubert Möllmann.

When Schmidt managed to break free from Möllmann's grip, he shot the teacher twice, hitting him in the stomach and shoulder, whereupon he proceeded to shoot out of a window at the children in the schoolyard, injuring five boys.

[12] According to letters he had written, Schmidt felt strong resentments against the Jesuits, calling them a danger to the German people and holding them responsible for the death of his father, a Protestant pastor, who had died the day before the shooting.