Police found dozens of guns in the Las Vegas shooter's hotel room and home.
But many of the details surrounding those weapons are still unknown.
"We have recovered 23 firearms at Mandalay Bay and 19 firearms at his home in Mesquite," Las Vegas Metropolitan Police Department Assistant Sheriff Todd Fasulo told reporters.
As of early Tuesday, authorities hadn't disclosed the specific type of weapons the gunman used during the attack. The shooting left 59 people dead and more than 500 others injured.
Las Vegas Metropolitan Police Sheriff Joseph Lombardo told reporters the rifles police uncovered range in caliber from .223 to .308, and some were equipped with scopes.
After listening to recordings taken during Sunday night's shooting, some experts say the gunman could have used a fully automatic weapon or a semiautomatic weapon that was modified to increase its firing speed.
At least two gun stores confirmed to the media they sold guns to the shooter after he passed all necessary background checks. It's unclear if those guns were used during Sunday night's attack.
According to the National Rifle Association, in the state of Nevada, you don't need a permit to purchase or possess a rifle, shotgun or handgun.
And you can legally purchase or possess a machine gun, which is a fully automatic weapon — so long as it's legally registered and possessed in compliance with all federal laws and regulations.
Police say they still haven't determined a motive for the attack.