On April 16, 2007, 32 people died after being gunned down on the campus of Virginia Tech by Seung-Hui Cho, a student at the college who later died by suicide.

The Virginia Tech shooting began around 7:15 a.m., when Cho, a 23-year-old senior and English major at Blacksburg-based Virginia Polytechnic Institute and State University, shot a female freshman and a male resident assistant in a campus dormitory before fleeing the building.

Police were soon on the scene; unaware of the gunman’s identity, they initially pursued the female victim’s boyfriend as a suspect in what they believed to be an isolated domestic-violence incident.

However, at around 9:40 a.m., Cho, armed with a 9-millimeter handgun, a 22-caliber handgun and hundreds of rounds of ammunition, entered a classroom building, chained and locked several main doors and went from room to room shooting people. Approximately 10 minutes after the rampage began, he died from a self-inflicted gunshot wound.

The attack left 32 people dead and more than a dozen wounded. In all, 27 students and five faculty members died in the massacre.

Two days later, on April 18, NBC News received a package of materials from Cho with a timestamp indicating he had mailed it from a Virginia post office between the first and second shooting attacks. Contained in the package were photos of a gun-wielding Cho, along with a rambling video diatribe in which he ranted about wealthy “brats,” among other topics.

In the aftermath of the Virginia Tech shooting, authorities found no evidence that Cho, who was born in South Korea and moved to America with his family in 1992, had specifically targeted any of his victims. The public soon learned that Cho, described by students as a loner who rarely spoke to anyone, had a history of mental-health problems.

It was also revealed that angry, violent writings Cho made for certain class assignments had raised concern among some of his professors and fellow students well before the events of April 16. In 2011, Virginia Tech was fined by the U.S. Department of Education for failing to issue a prompt campus-wide warning after Cho shot his first two victims.