The Aug. 3 shooting at the crowded Walmart has outraged Mexican leaders, with many in the country reeling from revelations the shooter may have targeted Mexican nationals. Foreign Minister Marcel Ebrard said Mexico would take legal action against the business that sold the shooter the firearm.
Ebrard added that Mexico's attorney general would declare Saturday's events an act of terrorism, which would give prosecutors access to information about the case. The attorney general would then decide whether to move forward with an extradition request for the 21-year-old suspect, Patrick Crusius.
"For Mexico, this individual is a terrorist," Ebrard said.
Investigators believe the shooter posted a rambling online manifesto in which he railed against a perceived "invasion" of Hispanics coming into the U.S. The shopping center where the shooting took place is about 5 miles from the main border checkpoint with Ciudad Juarez, Mexico. The shooting killed 22 people and wounded 24 others.
Tens of thousands of Mexican cross the border daily to work and shop in the city, which is more than 80 percent Latino, according to Census data.
On Monday, Mexican President Andrés Manuel López Obrador urged U.S. lawmakers to adopt gun control legislation in response to the massacre.
"There could be a change to their laws because it is stunning what is happening, unfortunate and very powerful," López Obrador said. "I don't rule out that they could change their constitution and laws. These are new times; you have to always be adjusting the legal framework to the new reality."
He added that Mexico doesn't want to interfere in the "internal affairs" of other countries, but said the Texas shooting reaffirmed his conviction that "social problems shouldn't be confronted with the use of force and by inciting hate."
Some in Mexico have put the shooting at the feet of President Trump, whose stirred resentment early in his presidential campaign when he described most Mexicans coming into the U.S. as "rapists" and "criminals." The U.S.-Mexico relationship was only further strained after Trump took office and vowed to build a border wall and slap tariffs on Mexican imports.
Former President Felipe Calderón said via Twitter that regardless of whether the shooting is a hate crime, Trump "should stop his hate speech. He should stop stigmatizing others."
The Associated Press contributed to this report.