As terrible as this seems, some institutions have nine populations. There are inmates who are under protection because they have not paid their debt; those who are under protection because they committed sexual offences; and biker gangs who can't stand each other.
I had a terrible time at Donnacona Institution in 1995. Members of the Rock Machine and the Hells Angels were in the same penitentiary at the same time. One night, a war broke out outside, then inside. They had to be separated. We were lucky. A correctional officer saved a lot of lives that night. He closed the door. One inmate was getting stabbed. A lot of things happened.
In an institution, just sending an inmate to the hospital means that all sectors are frozen. For example, if an inmate from block E is going, nobody moves because he cannot come in contact with the others.
There are nine different populations, for all sorts of reasons.