One blew himself up near a girls' academy, killing two students.
At the school, he shot and killed a security guard, a teacher and five students before turning the gun on himself, they said.
The young gunmen killed 12 students and a teacher before killing themselves.
The two killed 12 other students and a teacher before turning their guns on themselves.
He later left the classroom and killed two students in the school main hallway.
During the demonstration for democracy in 1989, Government troops killed more than 1,000 students and others.
The accident killed 11 students and a former student.
The fire, in January 2000, killed three students and injured more than 50 others.
They killed 12 students, a teacher and themselves in the worst school shooting in the nation's history.
But what's different is that two of its students killed 12 other students.
