Exclusive: New England Patriots star thanks Instagram follower who helped him thwart school shooting plot

NFL star Julian Edelman made an incredible catch off the field when he helped authorities thwart a potential high school shooting plot thanks to a tip on Instagram.

"At first I was like, 'I don't know if this is real,'" Edelman, a wide receiver with the New England Patriots, said in an exclusive interview on "Good Morning America" about the initial message.

In March, Edelman received a direct message from one of his Instagram followers alerting him of a comment posted on Edelman's Instagram account. The message threatened to shoot up a school.

"Dude," the Instagram user wrote. "There is a kid in your comment section, says he [is] going to shoot up a school. I think you should alert the authority."

Edelman said he called his assistant, Shannen Moen, who was in Boston.

"I said, 'Check this out. See what's going on with this. We've got to do something about this,'" Edelman recalled.

Moen told "GMA" she moved quickly and gathered as much evidence for authorities as possible.

"My initial thought was, my heart just sunk," Moen said. "And I first thought I need to go and find the comment, locate it. I did. I took screenshots of everything. I immediately called 911."

Local authorities in Boston immediately called police in Michigan, where the user was then located and identified as a 14-year-old high school student.

"Boston PD reached out to our department. Our on-duty supervisors immediately started looking into the information that was provided," said Capt. Joe Platzer of the Port Huron Police Department in Michigan. "We take these threats very seriously. We look into them very thoroughly. Like we tell everybody, if you see something, if you hear something, say something."

According to Platzer, police traced the message back to a 14-year-old boy in Port Huron. He said the teen was brought in for questioning and admitted to writing the threat.

Police also said they found two rifles in the teen's home that belonged to his mother.

"It's scary to think that those types of things can happen at a place of learning and a place where kids are going just to grow up in and meet with people and get social skills. I'd say that's a scary thing," Edelman explained.

The teen, whom police have not identified, was arrested and charged with making a false report of a threat of terrorism, which is a felony in Michigan.

According to Platzer, Port Huron detectives spoke to Edelman and credited him with bringing the threat forward. Without Edelman's reaction to the alarming social media post, police said, it's likely they would not have known about the threat.

But Edelman says the credit should go to the follower who alerted him about the threat and his assistant.

"I just want to say thank you for being the awesome human being that you are," the NFL star said in a message to the follower. "Keep on scouring, keep on going over all the comments. You're like the comment police, bro. We appreciate you."

ABC News' Enjoli Francis and Aaron Katersky contributed to this report.