Police say they thwarted what could have been a devastating mass casualty attack after arresting a transgender Nevada suspect accused of plotting a shooting on the Las Vegas Strip and uncovering an arsenal that included machine guns, grenade launchers and more than 50 firearms.
Allison Howlett, 36, who police identify in the arrest report as transgender, was arrested June 27 after Henderson police received a frantic 911 call from the suspect’s spouse reporting a domestic dispute, a stolen vehicle loaded with firearms and threats of both “suicide by cop” and a mass shooting.
Using vehicle tracking technology, Henderson police traced the stolen SUV to the parking garage at Sunset Station casino, where officers boxed in the vehicle after finding Howlett inside with loud music blaring and refusing repeated commands to surrender.
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Authorities said officers eventually convinced Howlett to lower a window by offering water before pulling the suspect from the vehicle and deploying a Taser during the struggle.
“It should be noted that the suspect had been sitting on a handgun and had access to a fully automatic, silenced MP5-style machine gun in the back seat of the vehicle, further corroborating the reported threats of suicide by cop and having the means to carry out a mass shooting,” Henderson Police Chief Reggie Rader said during a Tuesday news conference.
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Authorities say detectives recovered 22 firearms from the stolen vehicle, including handguns, rifles, a fully automatic firearm, suppressors, high-capacity magazines and hundreds of rounds of ammunition.
A subsequent search warrant executed at Howlett’s Henderson residence uncovered 30 additional firearms, including automatic weapons, an M2 .50-caliber machine gun, two Colt AR-style rifles equipped with M203 grenade launchers, seven suppressors and thousands of rounds of ammunition, investigators said.
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As the investigation unfolded, Henderson police enlisted the Las Vegas Metropolitan Police Department’s Southern Nevada Counter Terrorism Center, the FBI Joint Terrorism Task Force and the FBI’s Las Vegas Field Office.
Assistant Sheriff Dori Koren said investigators uncovered evidence that Howlett allegedly made threats over an extended period of time.
“Some of that information included the threat of wanting to become an active shooter or to conduct a mass attack here in Las Vegas,” Koren said.
Police also played audio during Tuesday’s news conference that investigators said was recorded in 2024 and captured Howlett allegedly threatening a future mass shooting.
“If the FBI doesn’t come … arrest me, there’s gonna be a … massacre. … One day … hundreds of people [are] going to lose their lives,” the person heard in the recording says.
“Obviously for our community here in Las Vegas, after dealing with One October, those types of threats are taken very seriously,” Koren said, referencing the 2017 Route 91 Harvest festival shooting, which authorities have called the deadliest mass shooting in modern U.S. history.
Investigators said the alleged threats, coupled with the cache of weapons, prompted the immediate expansion of the investigation into a counterterrorism case.
Howlett now faces 35 criminal counts, including making threats related to an act of terrorism, assault with a deadly weapon constituting domestic violence, grand larceny of a vehicle, 22 counts of grand larceny of a firearm, multiple weapons offenses involving machine guns, suppressors and short-barreled rifles, and resisting a public officer while armed with a firearm.
A Clark County judge later set Howlett’s bail at $500,000.
The investigation began after Julie Howlett called 911 to report that her spouse had allegedly taken her vehicle and threatened a mass shooting.
If you or someone you know is having thoughts of suicide, please contact the National Suicide Prevention Lifeline at 1-800-273-TALK (8255).
Julie Howlett later told FOX5 Las Vegas that the 22 firearms recovered from the stolen vehicle belonged to her and were part of her inventory as a gun dealer preparing to transport them out of state.
According to Julie Howlett, the confrontation began after she discovered Allison using her credit card without permission.
“That morning, I woke up to Allison spending money on my credit card,” Julie told FOX5. “She came in with a gun.”
Julie said she struggled to wrestle the firearm away after Allison allegedly pulled the trigger.
“She was going to kill me,” Julie said. “She took off. I ran outside. I had the gun still in my hand. I unloaded it.”
During Tuesday’s news conference, authorities confirmed investigators believe the firearms recovered from the vehicle belonged to the spouse. Officials said detectives are continuing to determine how the weapons were acquired, whether they were legally possessed and what role they allegedly played in the case.
Police have also alleged that Howlett made similar threats dating back to January 2024, including warning in a recorded statement that “there is going to be a mass shooting one day” if the FBI did not arrest the suspect.
Undersheriff Andrew Walsh said investigators are still working to determine a motive but warned the case highlights how rapidly violent threats can escalate.
“The time from thought to act — that window has closed,” Walsh said, explaining that suspected attackers today can move from making threats to carrying them out in a matter of days or even hours.
KSNV reported that during a recorded interview with detectives after the arrest, Howlett denied planning a mass shooting or threatening anyone.
According to the outlet, Howlett said she and Julie Howlett had been married for four years and were both transitioning to female while taking estrogen and progesterone. Howlett also told investigators she took Julie’s vehicle simply to leave after an argument, acknowledged knowing firearms were inside because Julie had planned to transport them out of state, and claimed users on the online communications platform Discord had falsely accused her of making threats.
KSNV further reported that Howlett said all of her personally owned firearms had previously been legally transferred to Julie through an ATF-approved process.
Walsh urged anyone who hears credible threats of violence, particularly in domestic situations, to report them immediately, saying early intervention gives law enforcement the best chance to prevent tragedy.
As Southern Nevada prepares for Fourth of July celebrations, officials said law enforcement agencies remain on heightened alert and credited the coordinated response between Henderson police, Metro, the FBI and other regional partners with stopping what investigators believe could have become a mass casualty attack.
Fox News Digital reached out to the Las Vegas Metropolitan Police Department and the FBI’s Las Vegas Field Office for additional comment. Both agencies said they had nothing further to add beyond officials’ remarks during Tuesday’s press conference.
Fox News Digital’s Adam Sabes contributed to this report.
