Police were called to Poughkeepsie High School Tuesday afternoon after multiple fights broke out in the building.
The large fight broke out around 1 p.m., which caused a "stay in place" to be issued.
City of Poughkeepsie police tell News 12 the fight happened as the school resource officer was looking into what caused a fight there earlier this year - a few incidents that News 12 has reported on.
The SRO and school staff were not able to de-escalate the situation. Because there were so many students involved, city and Town of Poughkeepsie police were needed.
There was no word if there were any injuries, but police say an ambulance was called for a student who was having trouble breathing.
Police are continuing an investigation into what happened. Any disciplinary action will be handled by the school district.