Clark County Sheriff Joseph Lombardo told reporters Monday that ammonium nitrate, a chemical compound used to make homemade bombs was found in the Las Vegas shooter’s car.

Stephen Paddock, 64, opened fire on concert-goers in Las Vegas, Nev., Sunday night killing at least 59 and injuring more than 500 people.

This is a new discovery in the investigation of the horrific shooting and comes after details emerged of how Paddock opened fire from the 32nd story of the Mandalay Bay hotel at 10:08 p.m. local time, into a crowd of 22,000 gathered at a Jason Aldean concert, and then killed himself. (RELATED: Deadliest Mass Shooter In US History Identified)

Ammonium nitrate is a high-nitrogen fertilizer and was also found in the well-known Oklahoma City bombing in April of 1995 when a truck-bomb explosion blew up the Alfred P. Murrah Federal Building in Oklahoma City, Okla., leaving 168 people deceased and hundreds injured.

Authorities identified Paddock of Mesquite, Nev., as the suspected gunman in the massacre. SWAT officers found him dead from a self-inflicted gunshot wound after breaching the door to his hotel room.

Investigators have yet to determine a motive in the shooting.

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