Police in California say a hotel worker may have prevented a potential mass shooting by a disgruntled colleague.
On Monday, the worker is said to have alerted police of "a verbal threat of violence" made by a co-worker at a hotel in the city of Long Beach.
Following an investigation, detectives identified 37-year-old Rodolfo Montoya as the individual behind the alleged threat.
Police believe he was upset over 'human resources issue' at work.
A search of the suspect's home turned up multiple guns, hundreds of rounds of ammo and tactical gear.
Among the items seized were an assault rifle and high-capacity magazines, which are illegal in the state.
Local police told reporters that the arrested man had "plans, intent and the means to carry out an act of violence that may have resulted in a mass casualty incident".
The suspect has since been charged with manufacturing and distributing assault weapons, possession of an assault weapon and making a criminal threat.
Chief of police Robert Luma said: "In recent months, we have seen several tragic incidents that have resulted in many lives lost.
"The witnesses who came forward and the diligence of our employees involved in this investigation very likely prevented a threat of violence and saved many lives."
The arrest comes amid increased calls for the US government to tighten gun laws in the wake of the mass shootings in El Paso, Texas and Dayton, Ohio earlier this month.