Texas school shooting is among deadliest in U.S. history. Here are some of the others

There have been dozens of shootings and other attacks in U.S. schools and colleges over the years, but until the massacre at Colorado’s Columbine High School in 1999, the number of dead tended to be in the single digits.

Since then, the number of shootings that included schools and killed 10 or more people has mounted. The most recent two were both in Texas.