Tuesday night’s riot at Spring Creek Correctional Center – the largest in the institution’s history – was a premeditated protest against a prison policy, state officials said at a press conference at the facility on Friday.

Officials refused to describe the prisoner’s grievances, however, leaving it unclear why around sixty inmates barricades themselves in their housing unit for most of Tuesday night.

Gov. Mike Dunleavy, Commissioner of Corrections Nancy Dahlstrom and Spring Creek Superintendent Bill Lapinskas were available for questions Friday at a press conference held inside Spring Creek’s Hotel Mod, where attendees briefly coughed and sneezed through lingering tear gas residue.

The riot began around 9 p.m. Tuesday night, Lapinskas said. The prisoner’s barricaded themselves in the module by stacking furniture against the entrance and began to destroy furniture and surveillance equipment inside, eventually doing around $100,000 worth of damage, according to estimates given at the press conference.

Inmates tricked the on-duty correctional officer into leaving the module with a routine request for supplies kept outside the mod, DOC spokesperson Sarah Gallagher later said, explaining why the inmates had the module to themselves.

“We knew instantly that their intent was to damage the facility, not to harm each other, Lapinskas said. “I think this was a well-planned-out riot. This was meant to send a very strong message.”

Asked directly what the inmates were protesting, Lapinskas declined to answer.

“At this point we are going to defer that to a later date,” Lapinskas said. “It is in our interest to defer that. … This was a protest regarding the way we do business.”

Lapinskas requested assistance from DOC “special operations response teams,” the corrections equivalent of SWAT teams on municipal police forces. Teams from Kenai and Anchorage arrived around 3 a.m. Wednesday morning, according to a DOC press release on the event.

Breaking a skylight on the modules roof, the teams lobbed tear gas grenades into the modules, permitting officers to make their first entrance since the protest began.

Lapinskas said that officers at that point removed several inmates “who did not wish to remain,” but it was unclear if these were prisoners who were not participating in the riot, or simply inmates who elected to surrender early.

Since the event, DOC has consistently given the number of involved prisoners as 62. Lapinskas confirmed at the press conference that that number includes every prisoner then housed at Hotel Mod, which has a capacity of 64.