Mexico President Enrique Peña Nieto says the attorney general will answer questions about an army killing of 22 people that a witness said was a massacre.
Peña Nieto says the federal prosecutor is digging into the facts, declining to comment further.
Peña Nieto spoke Monday to The Associated Press outside the United Nations after an economic conference.
The witness told the AP that soldiers killed 20 men and one woman after they had surrendered following a confrontation June 30.
The army said soldiers came under fire from armed men at an abandoned warehouse and returned fire in self-defense. The version came under question even before the witness because only one soldier was wounded. The AP found stray bullet marks and no signs of a massive shootout at the scene.