Holding a gun and carrying a knife in his backpack, a 27-year-old man caused panic when he opened fire from atop a pyramid within the sprawling complex that is one of Mexico's top tourism draws, officials said. He then took his own life.
Mexican officials said he acted alone, firing 14 times at the victims and at National Guard military police.
Literature about acts of violence
Documents in his possession referenced the 1999 Columbine school massacre in Colorado and indicated psychopathic behavior, said Luis Cervantes, attorney general of the State of Mexico, home to Teotihuacan.
"Among his belongings, authorities also found ... literature, images and documents allegedly related to acts of violence that ... may have occurred in the United States in April 1999," he said at the president's daily press conference. Cervantes added that the shooting appeared to be planned, and that the gunman had visited Teotihuacan, about 50 kilometers (31 miles) from Mexico City, many times before. Along with a gun, the shooter carried a plastic bag of 52 live .38 Special–caliber rounds."This act was not spontaneous," Cervantes said.
A tourist who witnessed the shooting told Reuters that visitors also heard the attacker mention Columbine, one of the most notorious mass shootings in U.S. history that has been said to inspire other attackers.
A separate person who also saw the shooting said he feared a higher death toll.
"He was firing and firing and firing and the bullets were making different sounds," Barak Hardley, a tourist from Los Angeles, told Reuters.
"I don't know why he stopped with one person. Thank God he did."
Tightened security measures for tourist sites
Mexico's security cabinet on Monday said 13 people were injured, including a 13-year-old and a 6-year-old. They hailed from Canada, the U.S., Colombia, Russia, Brazil and the Netherlands. Seven of the victims suffered gunshot wounds, Cervantes added on Tuesday.
"The state's response was immediate and forceful," Security Minister Omar Garcia Harfuch told reporters, adding that law enforcement will tighten security at archaeological sites and other top tourist sites.
Teotihuacan, a collection of towering pyramids and temples that were first occupied from 100 B.C. to 500 A.D. and later taken over by the Aztecs, attracted 1.8 million visitors last year, according to Mexico's tourism ministry.
The prized site will reopen on Wednesday with reinforced security, President Claudia Sheinbaum said.
She reiterated Mexico's guarantees of safety during the world's largest soccer event, which will open on June 11 in Mexico City before matches in other major Mexican cities, and said on Monday she met with FIFA staff, who organize the World Cup, to discuss logistics.
"We all know we had never seen anything like this in Mexico," she said. "From what prosecutors have indicated, this person showed signs of psychological problems and was influenced by incidents that had occurred abroad."
Sheinbaum had already faced questions about safety around the World Cup after the capture and death of drug kingpin El Mencho in March sparked violent episodes in various regions around the country.