The officer called for backup to arrest the suspect.
Houston police and security went to his room to collect his belongings, where they found ammunition all over the room, local NBC affiliate KPRC reported.
Police say responding officers found a rifle, a shotgun and a handgun in the man's room, plus ammunition.
When police arrived at the scene, the 21-year-old told police that he had a Ruger 9 mm that may have been stolen.
Just hours before New Year's celebrations, police arrested a man on multiple charges after discovering a small arsenal of guns in his top floor hotel room at the Hyatt Regency in Houston.More news: Vanity Fair Apologises For Video Suggesting Hillary Clinton Takes Up Knitting
Stanley was arrested and charged with trafficking heroin, four counts of possession of scheduled drugs, unlawful carrying of a pistol and simple possession of marijuana.
Police Lieutenant Gordon Macintosh said police were called to the Hyatt Regency Hotel shortly after midnight to deal with a "drunk, belligerent suspect".
Highest will be around Times Square in NY, where police said they would deploy rooftop observers and counter-snipers in more buildings than usual, as well as patrolling hotels. His name hasn't been released.
Police Chief Art Acevedo tweeted later on New Year's Eve that the threat had been 'contained'. Investigators say he was by himself and they are trying to figure out why he had the weapons.