I know in modern day, psych patients are escorted into a common area and counted during fire alarms if there's no actual fire. However, would they have been brought onto the grounds in the 60's?
So far, I've googled every permutation of "fire alarm history" I can think of. Fire alarm procedure 1960's, fire drill history, fire alarm 1960's hospital, etc. Wiki had a couple useless articles about what a fire alarm is and what a fire drill is, and the only thing I had any luck with was when the devices were invented.
(Also, a side note: I know deinstitutionalization started in 1963, but everything I've read says it didn't go into effect 100% immediately and was more of a "trickle.")