PORTSMOUTH — Kyle Hendrickson, a 25-year-old local man, will be charged for allegedly posting a video to social media outside Portsmouth High School with a gun and threatening to shoot up the school, according to city police.

The suspect remained at large Thursday morning, police said. He is not a Portsmouth resident, his current address is unknown and police believe he is the only person involved with the incident, according to Portsmouth Police Chief Mark Newport.

All city schools were closed Thursday after the Portsmouth Police Department received a tip about the threatening video, which local, state and federal authorities have been investigating since Wednesday night. Portsmouth police were notified of the video around 6 p.m. Wednesday.

According to city police, Hendrickson, who is “known to frequent the Seacoast area and southern Maine,” was sitting in a vehicle outside Portsmouth High School with a gun in the video.

“The message on the video said, ‘Imma gonna shoot up the school,’” police stated.

Criminal charges will be filed, police said.

The decision to close down schools in Portsmouth comes just over two weeks after a deadly school shooting in Nashville that claimed the lives of six people, including three 9-year-old students. In that massacre at the Covenant School, the shooter was killed by police minutes after making entry to the building.

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Update on investigation in Portsmouth

"Fortunately we were able to get ahead of this one, be proactive and investigate this threat to the point where we canceled schools as a cautionary measure to ensure that our schools are safe," Newport said.

FBI, DEA and local law enforcement have been working with Portsmouth police in the case, the chief said.

Asked Thursday morning if schools will be closed Friday, Newport said, "It's too early to make that decision."

Newport noted the threat was not specific to Thursday.

Zach McLaughlin, superintendent of schools for SAU 52 (Portsmouth schools), issued a statement mid-day Thursday:

"As we move through the day and get additional information, we will continue to update the school community. At the moment, we have made no decision regarding the status of schools for tomorrow. The School Department and Police Department continue to actively and closely collaborate during this situation. As I said last night, your support is greatly appreciated."

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How school officials reacted to threat

The city closed all schools on Thursday due to the online shooting threat, according to an alert from the school district sent out Wednesday evening.

McLaughlin notified district families of the decision late Wednesday night, informing the school community about the threat to “shoot up” the high school.

“As we are not currently in a position to feel that the threat is yet resolved, we need to make a decision regarding tomorrow’s school day,” McLaughlin wrote. “Out of an abundance of caution and a commitment to the safety of our school community, all Portsmouth schools will be closed tomorrow, April 13th. As the situation develops, I will be sure to provide you with updates as I am able.”

McLaughlin’s message to the district community was sent out shortly after 10:30 p.m. Wednesday.

“Finally, I just want to acknowledge the emotions of a moment like this,” McLaughlin added in his note. “It can be laced with fear, anger, and sadness. Amid this challenging time, we appreciate your support as we do our best to keep our students and staff safe.”

When reached for comment Wednesday night, McLaughlin could not disclose the details of the video, including who it appeared to be made by, what social media platform it was posted on and whether there was a direct threat made against any person in particular, due to the ongoing investigation.

The superintendent stated he hopes the investigation doesn't impact classes occurring in Portsmouth on Friday.

"I have a lot of faith in the Portsmouth community to weather something like this," he said. "It's a shame we've got to do it but we are a community strong enough to persevere through this and be really thoughtful for kids and families and staff."

In December, the Portsmouth and Dover school districts were two of several across the state to be the target of hoax school shooting calls, prompting lockdowns and police responses in public school systems around New Hampshire. The month prior, a minimum of 10 Maine schools, including Sanford High School, received similar unsubstantiated threats. Such false reports are referred to as swatting.

More: Police respond to hoax calls of school shooters in Portsmouth and Dover

In Maine: How hoax school shooting calls in Sanford, across Maine caused chaos

The New Hampshire Department of Safety’s Division of Homeland Security and Emergency Management stated Thursday morning that it was aware of the threat.

“All threats are taken seriously until such time as their validity is determined,” the department wrote in its release. “Everyone is encouraged to report any suspicious activity to their local law enforcement agency.”

This article originally appeared on Portsmouth Herald: Police identify Portsmouth High School shooting threat suspect