Child, Youth and Family (CYF) says it's working closely with police after allegations that staff assaulted students at an alternative school in Hamilton.
It's not known when the incidents took place, but police say their investigation is in its formative stage.
The Kauri Centre caters for students in CYF's care who, for a range of reasons, can't attend mainstream schools. It has 15 students, two teachers and four support staff.
The agency says it's helping police to interview staff and students about the allegations, involving physical abuse.
It says it would be inappropriate to provide any further detail at this stage.
The Ministry of Education says the investigation started after concerns were expressed by some of the students about being physically abused by staff.
It says the centre, which is closed for the holidays, won't be shutting permanently.