UPDATED at 3:05 PM PT with additional info: An arsenal of 18 weapons, explosives, and several thousand rounds of ammunition were retrieved from the Mesquite, NV home of the gunman who opened fire on a country music festival in Las Vegas, authorities said in an afternoon press conference.

The death toll now stands at 58 (not including shooter Stephen Paddock) in the deadliest mass shooting in modern U.S. history. The number of injured stands at 489, the city’s Sheriff Joseph Lombardo said in the presser (UPDATED October 4). Authorities also checked Paddock’s car and found ammonium nitrate, which is used in making explosives. Ammonium nitrate-based explosives were used in the Oklahoma City bombing in 1995, among other terrorist attacks.

In addition to the 18 weapons in the home, Paddock took 26 weapons to the hotel room at Mandalay Bay, which he used to open fire on the 22,000 concertgoers from his two-room suite on the 32nd floor. A motive has not been established, Lombardo said.

Authorities currently are working on four fronts, Lombardo described. They still are combing through the hotel suite where the gunman broke two windows using a hammer-like device to shoot down at concertgoers. Additionally, the music concert venue is being processed, as well as the home in the shooter’s Mesquite retirement community. A SWAT team also was about to hit another home owned by the gunman in northern Nevada, Lombardo said.

An FBI representative attending an earlier presser refuted ISIS’s claim of responsibility for the attack perpetrated by the retired 64-year-old accountant; the terror organization claimed the shooter recently converted to Islam, issuing that claim without evidence via its news agency Amaq.

“We have determined to this point no connection with any international terror group,” the FBI rep said, adding that they “continue to investigate.”

At an earlier presser, Lombardo said the shooter “killed himself prior to our entry” into his room at the hotel just across the Las Vegas Strip from the concert venue. He checked in to the hotel Thursday night, using the credit card of companion Marilou Danley, who is out of country.

The gunman waited until the performance of the headline act in the sold-out, three-day Route 91 Harvest festival concert to insure maximum attendance. Police said they are still seeking a motive.

The SWAT team that stormed the room found a cache of weapons indicating a planned-out attack. Lombardo reported at least 10 weapons were found in the hotel room, the exact location of which they were able to locate from the smoke detector. Audio of the shooting suggests at least one was a fully automatic weapon, causing maximum carnage.

Nevada has some of the country’s most relaxed gun laws; the state does not require firearm owners to have a license, does not require registration of weapons, and does not limit number of firearms someone can possess.

The lone shooter, Stephen Paddock, described as a pilot and a hunter, lived in a retirement community in Mesquite, about 80 miles outside Las Vegas; he may have been the community’s manager, authorities report.

The shooter’s brother told NBC News’ Tracy Conner his family was shocked, describing him as a guy who “went to hotels, gambled…went to shows,” was “basically retired,” had held a series of job over the years and “was just a guy.”

Around 3:50 AM PT, Lombardo had updated the death toll in the devastating shooting attack to 50. This is believed to make Sunday night’s event the biggest mass shooting in U.S. history.

Singer Jason Aldean was performing on stage when the shooting began. Witnesses said they initially thought the noise was fireworks before ducking and fleeing. Singer Jake Owen told Fox News, “There was no chance for people to get away… You couldn’t tell where it was coming from, it was loud and just non-stop… It’s a miracle not more people were injured.”

Police have made contact with the shooter’s housemate/girlfriend. Police were seeking two vehicles with Nevada plates and have asked for anyone with cell phone video that might prove useful to turn it over to the Las Vegas police.

Lombardo said at a morning news conference, “At approximately 10:08 PM, we had calls coming to dispatch of multiple shots being fired from the direction of the Mandalay Bay towards the Route 91 concert that was taking place on the East side of Las Vegas Boulevard… There was a shooter on 32nd floor of the Mandalay Bay. Officers engaged the suspect at that location. He is dead. He has been identified. He is a local resident. I will not release his name at this time.”

At that time, Lombardo described the gunman as a “lone wolf” type, adding, “We don’t know what his belief system was at this time.”

Although terrorism has not yet been evoked, the mass attack brings to mind the deadly November 2015 shooting at a rock concert in Paris that killed 89 people during a coordinated attack throughout the capital that left a total 130 dead.

Lombardo said in this case there are “no multiple shooters,” despite initial reports of incidents at other resorts. There are also “no explosives going off.” In May, more than 20 people were killed in a bombing at an Ariana Grande concert in Manchester, England.

In the immediate aftermath of the slaughter, flights in and out of McCarran Airport were temporarily suspended and locals were advised to say in their hotels and stay off the Strip, Vegas’ main drag.

Aldean released a statement on Instagram, saying: “Tonight has been beyond horrific. I still don’t know what to say but wanted to let everyone know that me and my crew are safe… It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night.”

The Mandalay Bay Resort also weighed in:

So did Celine Dion who is in residence at Caesars Palace: