April 4, 2014 5:20 PM EDT

A senior Army official said Friday that the mental condition of the Fort Hood soldier who killed three soldiers earlier this week may not have been the “precipitating event” in the shootings, suggesting that an “escalating argument” prior to the shootings may have been what sparked the deadly massacre off.

The remarks by Lt. Gen. Mark Milley at a press conference were a reversal from his comments Thursday, when he highlighted the “unstable psychiatric or psychological condition” of suspected shooter Army Specialist Ivan Lopez as a “fundamental underlying factor” in the shootings.

Lopez, 34, allegedly shot and killed three fellow soldiers—named by media sources as Sgt. 1st Class Daniel Ferguson, Staff Sgt. Carlos Rodriguez and Sgt. Timothy Owens—and injured 16 more before shooting himself dead. Army Secretary John McHugh, the army’s top civilian, told Congress on Thursday the suspect had been treated for depression, anxiety and sleep disorders.

But Milley said Friday that investigators were now looking into an altercation with another soldier that occurred shortly before the shooting as the primary cause. Theodis Westbrook, the father of one of the injured soldiers, told a CNN affiliate that his son had seen Lopez being denied a leave form on Wednesday afternoon. Shortly after, claimed Westbrook, the soldier returned with a gun and started shooting.

Texas Gov. Rick Perry and Sen. Ted Cruz (R—Tex.) visited Fort Hood on Friday to meet with wounded soldiers. “We’ll learn lessons about what occurred here and minimize the chances of this happening ever again,” Perry said.

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