How to react when a team of colleagues obviously made up some results?
my position at the university involves the management of the animals they used in the study

If your immediate supervisor is to be trusted, go to him or her.  If not, pick someone higher up in the university hierarchy.  You are looking for someone who will

protect your identity as a whistleblower

investigate discreetly

have enough influence within the university to be able to trigger effective action


Edit (in response to some comments): I should really have suggested that you look up your university's policy and procedures.  Let's look at what MIT has to say about &quot;Research Misconduct&quot; as an example.

Unethical behavior in research and scholarship strikes at the heart of the scholarly and educational enterprise. [...] Supervisors must enforce the highest standards for conducting research and creating and maintaining records of the research [...] specifically, laboratory and center directors....
Definitions: [...] Fabrication is making up data or results and recording or reporting them.
Duty To Report: Each member of the MIT community has a responsibility to report any conduct that he or she believes in good faith to be Research Misconduct at MIT. Ordinarily it is appropriate in the first instance for a Complainant to report his or her concerns to the supervisor of the prospective Respondent. [...] Consultation and guidance is always available from the Office of the Vice President for Research or from senior academic officers (deans, department heads, laboratory directors)....
A supervisor who becomes aware of possible Research Misconduct, either from his or her own observations or because of reports, has a responsibility to bring allegations of Research Misconduct directly to the Vice President for Research in order to ensure that proper procedures are followed.