You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
Four people are assisting police with their inquiries following a threat at Otago Boys' High School on Friday.
The online threat led to the school being evacuated, and nearby roads being cordoned off, for several hours on Friday morning.
Police raided a North Dunedin house on Friday afternoon, seizing several electronic devices including mobile phones and computers.
About a dozen pupils went to the exam at John McGlashan and about 70 boys went to St Hilda's to complete the physics exam.
A police media spokesman today said investigations into the incident were ongoing, and four people were "assisting with inquiries''.
Police are working through information collected and assessing its relevance.
''No arrests have been made at this stage.''