Julio Cesar Jasso Ramirez, the 27-year-old gunman behind Monday's shooting at Mexico's famed Teotihuacan pyramids, drew inspiration from pre-Hispanic sacrifices and the notorious 1999 US shooting at Columbine High School,

Mexican authorities identified Julio César Jasso Ramírez as the man who opened fire at the Teotihuacan pyramids, a 27-year-old Mexican national.

The front page of the Deseret News on April 22, 1999, as reporting continued from Littleton, Colorado, where an attack two days before at Columbine High School left 15 dead and many more injured. Editor’s note: This story was originally published on April 20,

Teenage sweethearts Nicholas Kunselman and Stephanie Hart-Grizzell survived the Columbine massacre in April 1999. Ten months later, they'd be shot dead in a crime that remains unsolved.

Students, parents, teachers and community members volunteered at several different locations for the Columbine Day of Service.

In 1999 it was unthinkable for someone to attack a school - that changed on April 23, 1999 when two Littleton, Colorado students entered Columbine High School armed with guns and explosives.

More than 1,200 Columbine High School students signed up to volunteer.

This week in history spans the depths of human tragedy through to the edges of the universe. The United States grapples with two harrowing flashpoints on its own soil: the apocalyptic end to the Waco siege and the Columbine high school massacre.

The gunman who opened fire at Mexico's Teotihuacan pyramid, killing a Canadian tourist, admired U.S. school shooters and Hitler, authorities said.