Two Iowa men were arrested and weapons were seized after police say threats were made to the Pokemon World Championships in Boston.

Police say 18-year-old Kevin Norton and 27-year-old James Stumbo had a 12-gauge shotgun, an AR-15, hundreds of rounds of ammo and a hunting knife in their vehicle.

Stumbo had posted a photo of the guns resting on a car Wednesday to a Facebook group called "Mayhem Pokemon Crew." The caption read "Kevin Norton and I are ready for worlds Boston here we come!!!"

Facebook

When another member of the group wrote "Good luck," Norton replied "With killing the competition?" The other member responded, "Haha yes."

Word of the post got to security at the Hynes Convention Center and they reported to Boston Police. When Norton and Stumbo tried to get in to the event Thursday, they were stopped.

Police let the men go pending a search warrant, but kept their car. They were then arrested Friday at the Red Roof Inn in Saugus, Massachusetts, after police discovered the weapons in the vehicle.

A senior Boston Police official tells NBC News that at this point, the threat does not appear to have a connection to any extremist groups such as ISIS. The motive behind the plot, however, remains a mystery to police.

One mother who attended the event with her child says they were never notified of a threat, though she heard rumors. She couldn't believe a family-friendly event like this would be seriously targeted.

"It's the best crowd, the best people. You lose your wallet, they'll hand it to you," said Tyra Williams of Illinois.

"I see no real reason," said Sergio Hernandez of Everett. "It's full of kids."

Hernandez says security was tighter than usual. Bags were checked carefully at the door.

"They checked our bags, they even checked little compartments," he said. "They thoroughly checked everything."

The Pokemon Company International issued the following statement:

"Prior to the event this weekend, our community of players made us aware of a security issue. 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 Pokemon Company International takes the safety of our fans seriously and will continue to ensure proper security measures are a priority."

Stumbo and Norton will be arraigned Monday.