Investigators in Arizona on Thursday reportedly recovered a military-style assault rifle in a vehicle rented by a man who they suspect of killing one person and wounding two others at an office building in Phoenix on Wednesday.

Mesa police confirmed that a body found in a Bass Pro Shop parking lot by a landscaper on Thursday morning matched the description of 70-year-old Arthur Harmon, the man suspected in the shooting. The body was found near a rented white Kia Optima that police believe Harmon used to flee after the shooting.

Police said that a handgun was found near the body, and the man had apparently died of a self-inflicted handgun wound.

On Thursday afternoon, Fox 10 KSAZ reporter Andrew Hasbun tweeted a photo of police standing by a white car and holding a military-style rifle in an evidence bag.

"Phoenix police pull assault rifle and ammo out of office shooting suspect Arthur Harmon's car," Hasbun captioned the photo.

There was no confirmation that the weapon in the photo had been used during the crime.

In a statement on Thursday, Phoenix law firm Osborn Maledon said that 43-year-old Mark Hummels, who was a partner at the firm, "will not survive from the shooting."

Police believe that Harmon shot Hummels and 48-year-old Steve Singer after a confrontation at their office on Wednesday over some type of litigation. Singer was pronounced dead later that day. Nichole Hampton, 32, was shot in the hand and was expected to recover.

As the shooting was taking place on Wednesday, National Rifle Association (NRA) chief Wayne LaPierre and Mark Kelly, the husband of former Arizona Rep. Gabrielle Giffords (D), were testifying to the Senate Judiciary Committee about assault weapons, high-capacity clips and universal background checks.

Kelly referenced the incident, describing “what seems to be a shooting with multiple victims with multiple shots fired.”

Watch this video from KSAZ, broadcast Jan. 31, 2013.