(NewsNation) — Eighteen students and one adult were killed Tuesday when a gunman opened fire at an elementary school in Texas, becoming the deadliest school shooting since a gunman killed 26 people at Sandy Hook Elementary School in 2012.

Officials say 18-year-old Salvador Ramos was armed with a handgun and a rifle and was wearing body armor when he went into Robb Elementary School in Uvalde, Texas on Tuesday afternoon and began shooting indiscriminately.

The country has seen dozens of deadly shootings at schools, including six in the last two decades in which more than 10 students were killed. In 2022, there have been 38 shootings at K-12 schools and colleges in the U.S., according to CNN.

Here’s a look at some of the deadliest mass shootings in U.S. history:

Virginia Tech University – 33 dead

Marking the deadliest school shooting in U.S. history, 33 people were killed on the campus of Virginia Tech in 2007 when 23-year-old college student Seung-Hui Cho opened fire in various buildings on campus using two semi-automatic pistols.

Cho shot and killed two students in a dormitory before he traveled to a classroom building, where he chained the doors shut and then began firing into classrooms, killing 30 more people.

Cho shot and killed himself when police stormed the building.

Sandy Hook Elementary School – 27 dead

On Dec. 14, 2012, 20-year-old Adam Lanza shot and killed his mother at their home in Newtown, Conn. before he traveled to Sandy Hook Elementary school, where he killed 26 more people, including six staff members and 20 children, ages 6 and 7.

Most of the killings occurred in two first grade classrooms that Lanza forced his way into. Around 9:40 a.m. police heard the last gunshot and found Lanza dead from a self-inflicted gunshot wound.

Lanza was found with his mother’s Bushmaster XM-15-ES2 rifle and 10 magazines with 30 rounds each. He also had two handguns with him. All three weapons were semi-automatic.

Marjory Stoneman Douglas High School – 17 dead

Fourteen high school students, ages 14-18, were killed along with three staff members at Marjory Stoneman Douglas High School in Parkland, Florida when 19-year-old former student Nickolas Cruz opened fire in the school.

Cruz entered the high school armed with an AR-15 rifle and multiple magazines. He traveled the three floors of the high school, firing into classrooms and shooting staff and students stranded in hallways. He killed 17 people in six minutes.

Cruz escaped the school by blending in with fleeing students and then went to a fast-food restaurant and a mall before police captured him.

He was convicted of 17 counts of first-degree murder and 17 counts of attempted first-degree murder.

Columbine High School – 15 dead

The shooting at Columbine High School, which left 15 people dead, shocked the country at the end of the last millennium.

High school seniors Eric Harris and Dylan Klebold opened fire in Columbine High School using pistols, pump shotguns and a carbine rifle to kill 15 students.

Santa Fe High School – 10 dead

Dimitrios Pagourtzis, a 17-year-old high school student, opened fire in an art classroom at Santa Fe High School in Texas, killing eight of his classmates and two teachers with a pump-action shotgun and a revolver.

Pagourtzis engaged in a shootout with two police officers stationed at the school. He critically injured one of them before eventually surrendering to police after being injured himself in a shootout with officers who entered the school.

Red Lake Senior High School – 10 dead

On March 21, 2005, 16-year-old Jeff Weise killed his grandfather and his grandfather’s friend at their home on Red Lake Indian Reservation in Minnesota, before then using his grandfather’s police weapons to kill seven more people at Red Lake Senior High School.

Weise killed five students, one security guard and one teacher at the school before he turned his weapon on himself and took his own life.

Umpqua Community College – 10 dead

Eight students and a professor were killed at Umpqua Community College in Roseburg, Oregon when 26-year-old gunman Chris Harper-Mercer opened fire on campus.

Harper-Mercer exchanged gunfire at the scene with officers, who struck him once before he shot himself in the head.

The youngest victim was 18; the oldest was 67.