Pokémon World Championships is being held from Friday until Sunday

Both of the men had been invited to contest under the 'Masters Division'

Norton and Stumbo have now been arrested on multiple firearm charges

Cops discovered gun, rifle, hordes of ammunition and a knife in their car

Men were stopped while trying to enter the tournament building in Boston

He also posted photo of shotgun and AR-15 rifle laid on the back of a car

Police have foiled an alleged plot to carry out a mass shooting at this weekend's Pokémon World Championships after two gunmen apparently boasted about their violent plans on social media.

Kevin Norton, 18, and James Stumbo, 27, attracted investigators' attention after they reportedly threatened to cause harm to thousands of attendees at the tournament in Boston, Massachusetts.

Although the details of these threats remain unclear, Stumbo had posted a photo of a 12-gauge shotgun and an AR-15 rifle, laid on the back of a white car, on Facebook earlier this week.

Alongside the image, he had written: 'Kevin Norton and I are ready for Worlds. Boston here were come!!!'. Norton, meanwhile, had joked in a comment about 'killing the competition' at the event.

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Suspects: James Stumbo (left), 27, and Kevin Norton (right), 18, attracted investigators' attention after they reportedly threatened to cause harm to thousands of attendees at the Pokémon World Championships

Chilling: Although the details of these threats remain unclear, Stumbo had posted a photo of a 12-gauge shotgun and an AR-15 rifle, laid on the back of a white car (pictured), on Facebook earlier this week

Alongside the image, he had written: 'Kevin Norton and I are ready for Worlds. Boston here were come!!!'

'Mass shooting plot': Norton, meanwhile, had joked in a comment about 'killing the competition' at the event

After private sector security staff at Hynes Convention Center - which is hosting the competition - alerted intelligence officials to the deadly threats on Thursday, an investigation was launched.

Hours later, the two men were stopped while trying to enter the center. It is unclear why they were attempting to access the building on Thursday - one day before the tournament kicked off.

When detectives searched the pair's car, they found the Remington shotgun and DPM5 Model rifle, as well as several hundred rounds of ammunition and a hunting knife, police said in a statement.

Neither Norton nor Stumbo, both from Iowa, could produce a license to carry.

The suspects were arrested at a hotel in Saugus, and have now been charged with unlawful possession of a firearm, unlawful possession of ammunition, and other firearms counts.

They will shortly be arraigned at Boston Municipal Court, police said.

On Saturday, Boston Police Department Bureau of Intelligence and Analysis Commander Supt. Paul Fitzgerald said of the arrests: 'The relationship between police and private sector security is important in both our community policing philosophy, as well as our counter-terrorism strategy.

Discovery: Cops found the Remington shotgun and DPM5 Model AR-15 rifle, as well as several hundred rounds of ammunition, and a hunting knife (all pictured) inside the car of Norton and Stumbo, both of Iowa

Shooter: After private sector security staff at Hynes Convention Center alerted intelligence officials to the deadly threats on Thursday, an investigation was launched. Above, Norton shoots a gun in a Facebook photo

Arrest: Hours after the inquiry was started, the two men were stopped while trying to enter the center. It is unclear why they were attempting to access the building on Thursday. Above, Stumbo poses with a canon

'This incident is a good example of private security reaching out to their local Boston police district and relaying information to detectives and BRIC analysts in order to identify the very real threat.'

He added that officials had done a 'great job' in preventing a 'potential tragedy'.

In a statement, the Pokémon Company told Fox News that attendees had informed them of the social media threats earlier this week, prompting them to alert staff at Hynes Convention Center.

'Prior to the event this weekend, our community of players made us aware of a security issue,' the firm said. 'We gathered information and gave it as soon as possible to the authorities at Hynes Convention Center who acted swiftly and spearheaded communication with Boston Police.

Nintendolt: Both Norton and Stumbo were invited to the tournament under the Masters Division. The two men remain in police custody. Above, Stumbo is pictured (left, in black) at a Pokémon convention in 2010

Location: In a statement, the Pokémon Company said that attendees had informed them of the social media threats earlier this week, prompting them to alert staff at Boston's Hynes Convention Center (pictured)

'Due to quick action, the potential threat was resolved. The Pokémon Company International takes the safety of our fans seriously and will continue to ensure proper security measures are a priority.'

The Pokémon World Championships, which is an invitation-only event, ends on Sunday. The annual competition features the top video game and trading card game players from across the world.

Players compete for more than $500,000 in scholarship prizes.

According to the New York Daily News, both Norton and Stumbo are Pokémon fans who were invited to the tournament under the Masters Division. The two men remain in police custody.

The FBI is assisting cops with the investigation.