The authorities in Mexico are still piecing together how a typical morning at the ancient pyramid complex of Teotihuacán, one of the country's foremost tourist destinations, descended into terrifying gun violence on Monday. The video footage is disturbing. A gunman stands atop the imposing Pyramid of the Moon and opens fire on the tourists around him, who cower for cover among the pre-Hispanic stone structures. After the ordeal, a 32-year-old Canadian woman had been killed and the gunman had died from a self-inflicted gun wound. Tourists from several nations, including Russia, Colombia and Brazil, were treated for their injuries in local hospitals. The fact that visitors from overseas were targeted poses a headache for the government just weeks before Mexico co-hosts the men's football World Cup. The shooting came less than two months after masked gunmen from the Jalisco New Generation Cartel unleashed a wave of violence. However, Mexican authorities say the Teotihuacán gunman, identified as 27-year-old Julio César Jasso Ramírez, acted alone with no apparent ties to organized crime. They discovered materials related to previous mass shootings in his possession, raising alarms about the possibility of copycat incidents and the influence of U.S. gun violence culture. While Mexico has its own issues with crime and violence, the incident reflects a shift towards individual acts of mass violence, causing increased concern ahead of a major international event.