Police Say They Thwarted Mass Shooting in Las Vegas Casino Garage

A woman accused of plotting a mass shooting was arrested over the weekend after police intercepted her in a casino parking garage with an arsenal of firearms, authorities announced Tuesday (June 30).

Henderson, Nev. police said they first became aware of the threat on Saturday, June 27, when a woman called 911 at 9:38 a.m. to report that her ex-spouse, 36-year-old Allison Howlett, had stolen her vehicle — and that the car contained multiple guns.

The caller also warned dispatchers that Howlett had threatened to carry out a mass shooting and commit “suicide by cop.”

Officers arrived at the caller’s home around 10 a.m. and learned the vehicle was equipped with a location‑tracking system. The tracker showed the car in the vicinity of Henderson’s Sunset Station Casino, about 10 miles southeast of the Las Vegas Strip.

By 11:17 a.m., Henderson police — working with Sunset Station security — located the vehicle in the parking garage. Howlett was in the driver’s seat, playing loud music and refusing repeated commands to exit. Officers boxed the vehicle in with patrol cars to prevent her escape.

Police negotiators eventually convinced Howlett to roll down the window. When she asked for water, they used the moment to grab the hand she used to reach for the bottle and tased her, facilitating her removal from the vehicle.

Large Arsenal Recovered

Police recovered 22 firearms and hundreds of rounds of ammunition from the vehicle, including a handgun Howlett was sitting on and a fully automatic, silenced MP5-style submachine gun in the back seat.

A search of her Henderson residence uncovered an additional 30 firearms — including automatic rifles, suppressors, and high-capacity magazines — for a total of 52 firearms.

After Howlett’s arrest, Henderson police contacted the Las Vegas Metropolitan Police Department’s Southern Nevada Counter Terrorism Center, which identified several threats allegedly made by Howlett over a period of years — including explicit statements about wanting to become an active shooter.

At Tuesday’s briefing, authorities played a 2024 audio recording in which a voice they identified as Howlett’s threatened to carry out a mass attack if federal agents did not intervene.

Authorities said they are still working to determine a motive. FBI Special Agent in Charge Christopher Delzotto credited the swift coordination between Henderson police, LVMPD, and federal agencies with preventing what could have been a mass‑casualty event.

Howlett was booked into the Clark County Detention Center and faces multiple charges, including making a threat related to an act of terrorism, assault with a deadly weapon constituting domestic violence, grand larceny of a vehicle, grand larceny of a firearm, and resisting a public officer with a firearm.

An arraignment is scheduled for 9 a.m. Wednesday, July 1, in Henderson Justice Court. Federal charges have yet to be filed.