Wellington High School was in lockdown earlier this morning after police received a report of a threat in the area.
The school published an update at around 10.15am, saying the "situation had been resolved with police support".
Wellington High School Principal Dominic Killalea said everyone had responded to instructions and all students, staff and persons on-site had been accounted for.
A police spokesperson said two people were being spoken to about the incident, and police would remain in the area as a precaution.
Earlier in the morning police had received "credible information about a threat to the school" over social media.
All entry points into the school had been locked, with students remaining in their classrooms and exams continuing, an earlier post read.
This morning's NCEA exams included level one business studies, level two biology, level three German, Chinese, agricultural and horticultural science, and scholarship English.