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, sowing fear across the country following the killing of their leader 'El Mencho' by the security forces.

But this incident was very different. Mexican authorities say the Teotihuacán gunman acted alone and there was no apparent link to Mexico's widespread cartel violence.

He has been identified as 27-year-old Julio César Jasso Ramírez, a Mexican citizen who lived in Mexico City. 'The aggressor planned and carried out the attack on his own and there is absolutely no indication at this point that he had any external help or that any other individuals were involved in this incident,' said Attorney-General of Mexico State José Luis Cervantes Martínez.

Among the gunman's belongings, officials found a handgun, a bag of cartridges, and a tactical knife. Notably, they also found literature and manuscripts appearing to reference acts of violence related to the Columbine High School shooting in the U.S.

Valeria Villa, a Mexican family therapist, expressed concern that this shooting represents a shift towards a pattern of mass killings by lone individuals, reminiscent of events seen in the U.S.

President Claudia Sheinbaum, emphasizing her commitment to securing safety for tourists, expressed condolences to victims' families immediately after the attack. However, fears surrounding tourist safety have heightened, particularly as the World Cup approaches, amidst a backdrop of ongoing violence in Mexico's history.