Reuters reports that “the suspected gunman at Fort Hood in Texas argued heatedly with fellow soldiers before going on a shooting spree that left three dead and 16 injured at the expansive U.S. Army base, a military investigator said on Friday.”  

“The suspected shooter Ivan Lopez, a 34-year-old soldier battling mental illness, then turned the gun on himself in the second mass shooting at the base in the last five years.”  

“‘We do have credible information he was involved in a verbal altercation with soldiers from his unit just prior to him allegedly opening fire,’ Christopher Grey, of the U.S. Army Criminal Investigation Command, told a news conference, without offering further details.  

“‘At this time, we have not established a concrete motive,’ Grey added.”