Two men from Iowa were arrested on gun charges after police said they threatened violence against fellow competitors at the Pokemon World Championships, which were held this weekend in Boston, Massachusetts.

James Stumbo, 27, and Kevin Norton, 18, were charged with unlawful possession of a firearm, unlawful possession of ammunition and other firearm-related charges, Boston Police said in a Sunday press release.

“The (Boston Police) detectives and collaborating agencies did a great job in the stop and prevention of a potential tragedy,” said Paul Fitzgerald, commander of the department’s Bureau of Intelligence and Analysis.

Here’s what you need to know:

1. Norton Posted on Facebook About ‘Killing the Competition’

On August 19, James Stumbo posted a photo of two guns on the trunk of a car on the Mayhem Pokemon Crew Facebook page with the caption, “Kevin Norton and I are ready for worlds Boston here we come!!!”

After a person named Joey Faux posted, “Good luck!,” Norton responded, “With killing the competition?”

Stumbo and Norton appeared in court Monday for the first time.

According to WCVB, police said other online posts referenced the Columbine shooting and “another Boston massacre.”

The duo was held without bail and are scheduled to appear in court again on September 1.

2. A Tip Was Provided to Police by the Convention Center’s Security

According to police, the Boston Regional Intelligence Center was given information by private security personnel at the Hynes Convention Center about threats of violence made over social media to attendees of the Pokemon World Championships on Thursday.

The security officers and Boston Police began investigating and then stopped Stumbo and Norton while they were trying to enter the event. The detectives found that the two men had firearms in their vehicle, but they couldn’t produce a license to carry them. The vehicle was then seized.

“The relationship between police and private sector security is important in both our community policing philosophy, as well as our counter-terrorism strategy,” said Paul Fitzgerald, Boston Police’s Bureau of Intelligence and Analysis Commander. “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.”

3. Police Seized 2 Guns, a Knife & Hundreds of Rounds of Ammunition

Police said they served a search warrant on August 21 on a vehicle belonging to one of the suspects. Detectives found a 12-gauge Remington shotgun, a DPM5 Model AR-15 rifle, several hundred rounds of ammunition and a hunting knife.

They then issued an arrest warrant for James Stumbo and Kevin Norton, and the duo was taken into custody at a hotel in Saugus, Massachusetts.

4. Stumbo & Norton Were Invited to Play in the ‘Masters Division’

Both Stumbo and Norton were scheduled to play in the Masters Division of the Pokemon World Championships, according to the Pokemon website.

Stumbo is featured in multiple YouTube videos talking about Pokemon tournaments he has participated in.

Josh “Squeaky” Marking, who interviewed Stumbo in one of the videos, told Kotaku that Stumbo is a “fairly reserved guy,” adding, “Every time I did an interview with him he always seemed like a chill person but he is also the type to be sarcastic and joke around.”

Marking told the gaming website that Stumbo is a “self proclaimed gun enthusiast,” who might have been making a joke with the Facebook post.

5. Nearly 1,000 Pokemon Players Were Invited to the Championships

The Pokemon World Championships included nearly 1,000 invitees from around the world in the masters, senior and junior divisions, according to the Japanese card game’s website.

The tournament began Friday and was set to end on Sunday.

“Prior to the event this weekend, our community of players made us aware of a security issue,” Pokemon Company International said in a statement. “We gathered information and gave it as soon as possible to the authorities at the John B. Hynes Veterans Memorial Convention Center who acted swiftly and spearheaded communication with the Boston Police Department. 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.”

According to a reporter for Vice’s Motherboard who was at the event, attendees were not told about the alleged threats.

“All weekend, security seemed extra tight—I’ve been to gaming conventions before, where there was little-or-no police presence. As I mentioned, at this year’s World Championships, police were everywhere, on each floor of the convention center and in all of the major conference rooms,” Jason Koebler wrote. “The roughly 3,000 attendees were screened and bags were checked, dogs patrolled every area. All of this seemed to be overkill to me, but that’s because we were kept totally in the dark about any threats.”