Police are speaking with two young people after a threat was made against Wellington High School.
The school's principal says police told him the person who made the threat had posted images on social media that linked them to far-right and Nazi extremism.
The school was locked down earlier this morning after the threat was posted on social media and reported to police.
"The threat made reference to Wellington High School, which was placed into partial lockdown for around one hour as a precaution while the incident was dealt with," police said in a statement this afternoon.
Inquiries into the matter are continuing.
The shooting was allegedly planned for 2021 but was moved forward after messages sent by the alleged shooter were passed on to school staff, a student told Stuff.
Police have also clarified there was currently no information to suggest any particular group was a specific target, after media reports the threat related to the LGBTQI+ community.
"Police would like to thank Wellington High School and the wider community for their co-operation while the threat incident was dealt with.
"We know this incident has been worrying and we urge anyone with concerns about their safety or the safety of others to speak to police immediately to report it."
Anyone with information relating to the incident could contact police on 105, quoting file number 201126/3921.
In an email to Wellington High School parents this afternoon principal Dominic Killalea said he could assure them nothing police reported to him had any link with the Rainbow community.
"I do not know if there is any link and I am sure we will learn more in coming days - the only thing that police told me about the incident was that the person had posted images on social media that linked him to far-right and Nazi extremism."
Killalea said the situation this morning was challenging and teachers and students responded "wonderfully".
"There were, of course, students trying to do exams and many of them may have been affected by the information being received this morning."
He said there was a derived grade process that could be used for students affected by the morning's events.
This morning's NCEA exams included level one business studies, level two biology, level three German, Chinese, agricultural and horticultural science, and scholarship English.
Killalea said earlier they were made aware of a "serious and imminent threat" and took immediate steps to make sure the students were safe.