(Courtesy: U.S. Army)
(Courtesy: U.S. Army)

More details are being released about last week's deadly shooting at Fort Hood as the Army prepares to host the President and First Lady at a memorial service on Wednesday.

FOX News Radio's Tonya J. Powers reports:

Investigators say an altercation over a request for leave may have triggered Specialist Ivan Lopez's shooting rampage at Fort Hood last Wednesday.

Chris Grey is the spokesman of the Army's Criminal Investigation Division.

(Grey) "We have not confirmed a definitive motive, but are doing everything possible to do so."

Grey said the crime scene covered the equivalent of two city blocks as Lopez drove from one area of the post to another, firing at soldiers.

Lopez killed three and hurt 16 before taking his own life.

Tonya J. Powers, FOX News Radio.

Fort Hood

LISTEN to FOX News Radio's special coverage of Monday's Fort Hood press conference: