Emergency services were called to the Ara Institute of Canterbury in Timaru in Arthur St about 10am and buildings were evacuated as a precaution.
Cordons were put in place between Arthur St, Grey Rd, North St and State Highway 1 (Theodosia St) and people asked to avoid the area and take alternative routes.
Police said at 2.50pm the cordons had been lifted.
"Specialist search teams have finished an examination of the property and not located anything of concern."
Leonie Rasmussen, the polytech's Timaru campus manager, said staff quickly responded to a perceived risk to students by taking appropriate precautions, calling police and evacuating the buildings.
"Because of the likely time it will take for police to complete their processes, the decision was made to close the campus for the day."
About 250 staff and students were affected, she said.
"Students gathered safely with ongoing support from staff and student advisers.
"Around 45 students who travel to the Ara campus by bus are being cared for and return buses have been ordered early today. Those with belongings left in classrooms have been assured these will be kept safe by Ara staff once they can access the buildings."
Any whanau with concerns should contact the team at 0800 242 476.
