Sunday's massacre, which authorities are calling an act of domestic terrorism, was just the latest in a string of mass shootings in the nation.
At least 49 people were killed and another 53 wounded this weekend after a gunman opened fire and took hostages at Pulse, a gay nightclub in Orlando, Florida, in the deadliest single-day mass shooting in American history.
Sunday’s massacre, which authorities are calling an act of domestic terrorism, was just the latest in a series of recent mass shootings in the nation.
Read: First Orlando Victims Named as Families Anxiously Wait for News About Their Loved Ones
Here are five of the other deadly mass shootings in the country's modern history.
32 Killed in the Virginia Tech Shooting on April 16, 2007
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Virginia Polytechnic Institute and State University student Seung-Hui Cho fatally shot 32 people —including 27 fellow students and five faculty members — and injured 17 others in two separate attacks on the Blacksburg campus before turning the gun on himself.
After the shooting, NBC News received writings, photographs and video that Cho sent the station, in which the 23-year-old gunman complained about being bullied and ranted about “brats.”
The American Psychiatric Association urged the media to stop airing his so-called manifesto, saying in a statement: “The publicity of the Cho materials not only seems insensitive to the grieving and traumatized families, friends and peers of those murdered and injured, but also seriously jeopardizes the public’s safety by potentially inciting 'copycat' suicides, homicides and other incidents.”
27 Killed in the Sandy Hook Elementary School Shooting on December 14, 2012
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Gunman Adam Lanza killed 20 first-graders, all ages 6 and 7, as well as six adult staff members and himself at Sandy Hook Elementary School in Newtown, Connecticut.
Before opening fire at the school, Lanza shot and killed his mother, Nancy Lanza, at their Newtown home. The 20-year-old’s motive for targeted the school was never established.
Lanza suffered from extreme mental health issues that were left untreated and he was preoccupied with violence, a report from the Office of the Child Advocate found.
"[Lanza], who over the years engaged in recreational shooting activities with both of his parents, retained access to numerous firearms and high capacity ammunition magazines even as his mental health deteriorated in late adolescence," the report said.
23 Killed in Shooting at Texas Restaurant on October 16, 1991
After 35-year-old George Hennard drove his pickup truck into Luby’s Cafeteria in Killeen, Texas, he sprayed bullets on the packed eatery before fatally shooting himself.
As he began shooting, Hennard — who was described by others as an angry and withdrawn man who disliked women and minorities — reportedly yelled: "All women of Killeen and Belton are vipers! This is what you’ve done to me and my family! ... This is payback day!"
Twenty-three people were killed and 27 others were wounded in what was, until Sunday, the U.S.’s deadliest shooting to occur outside a school.
21 Killed in McDonald’s Massacre on July 18, 1984
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Former security guard James Huberty, 41, shot and killed 21 people and wounded 19 others before he was fatally shot by a police sniper in San Ysidro, California.
Huberty brought a cache of weapons and ammunition to the McDonald’s restaurant on San Ysidro Boulevard, where 45 customers were dining. Inside, he shot two employees and ordered everyone on the ground before opening fire on a customer who tried to convince him to stop. He went on to kill additional employees and customers — including a pregnant woman, children, an infant and the elderly — before he was killed.
18 Killed in University of Texas at Austin Shooting on August 1, 1966
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Former U.S. Marine Charles Joseph Whitman opened fire from the top of a tower at UT Austin, where he killed 16 and wounded 32. He began to encounter return fire from police and armed civilians before he was fatally shot by an officer who managed to climb to the top of the tower undetected.
Police determined the 25-year-old had stabbed his wife and mother to death before making his way to the university. His mother had also been shot in the back of the head.
Read: America Pays Tribute to Orlando Victims As Hundreds Line Up To Donate Blood
After “calmly purchasing guns and ammunition from three stores and preparing an elaborate trunk full of supplies, he had ascended the Tower to continue his murderous action which left 16 dead and 32 wounded,” the Connally Commission — established to investigate the massacre — wrote at the time.
Whitman, who studied architectural engineering at the University, had complained of physical and mental health issues before the shooting. An autopsy revealed he had a malignant brain tumor, but it could not be determined if it had affected his deadly actions.
Watch: Son Who Texted Mom From Bathroom During Orlando Shooting is Among The Victims
