Dec. 14, 2012 -- As the numbers of the dead from a Newtown, Conn., elementary school shooting climbed into the double digits, it's hard not to remember that we have been here before.
The Sandy Hook elementary school shooting is the deadliest at a high school or grade school in the history of the country, but it is far from the first. Several mass school shootings have speckled our recent history.
Thirteen years ago, the small community of Littleton, Colo., was rocked by a massacre at Columbine High School. Gunmen Eric Harris, 18, and Dylan Klebold, 17, walked into their school on April 20, 1999, and opened fire, killing 12 of their classmates and a teacher, and injuring 21 more, before turning their firearms on themselves.
At the time, it was dubbed the most deadly school shooting in American history, and it changed the way many communities across the country thought about school safety.
But then the nation was once again rocked to its core when a gunmen went on a terrorizing rampage at Virginia Tech, almost a decade later.
On April 16, 2007, Virginia Tech senior Seung-Hui Cho unleashed a rampage on the college campus, shooting and killing 32 students, and wounding 17 more people. More than a year before the massacre, in December 2005, a district court in Montgomery County, Va., deemed Cho "mentally ill" and "an imminent danger to self and others."
The aftermath of the Virginia Tech shooting prompted Congress and President George W. Bush to sign the first major change to U.S. gun laws in more than 10 years -- it expanded the federal background check database -- and overhauled how many campuses handle crime and security alerts.
Before these rampages, there were multiple other fatal school shootings. The death toll wasn't as high, but the violence was just as great.
This year, on Feb. 27, T.J. Lane, 18, allegedly entered Chardon High School in Ohio with a .22 caliber handgun and a knife. He shot four students in the cafeteria and one in the hallway before walking out, leaving three dead. Police detained him within a mile of the school. He remains in custody and is expected to stand trial for the shootings in January.
On Oct. 2, 2006, a gunman took about a dozen girls hostage, killing at least three of them, at a one-room Amish schoolhouse in Pennsylvania's Lancaster County, police said. The shooter was among the dead when police arrived.
On March 21, 2005, 16-year-old Jeff Weise shot and killed five classmates, a teacher and an unarmed guard at a high school on the Red Lake Indian Reservation in Minnesota, where about 5,000 Native Americans live, before taking his own life. Weise had killed his grandfather and his grandfather's companion before heading to school that day.
Between late 1997 and early 1998, there were three school shootings within months of one another.
On May 21, 1998, two teenagers were killed and more than 20 people were hurt when 15-year-old Kip Kinkel opened fire at a Thurtson High School in Springfield, Ore., after killing his parents. Kinkel was sentenced to nearly 112 years in prison.
On March 24, 1998, two boys, ages 11 and 13, fired on their Jonesboro, Ark., middle school from nearby woods after pulling the fire alarm, killing four girls and a teacher, and wounding 10 others. Both boys were later convicted of murder and were incarcerated until they turned 21.
On Dec. 1, 1997, three students were killed and five wounded at Heath High School in West Paducah, Ky. Michael Carneal, 14, and a freshman, later pleaded guilty but mentally ill to murder charges and is serving life in prison. He is eligible for parole in 2023.
One of the most iconic school shootings in American history remains at Kent State Univeristy in Ohio. On May 4, 1970, Ohio National Guard troops opened fire to quell an anti-Vietnam War demonstration, killing four students and wounding nine others. The shooting became known as the May 4 Massacre