Most of them died instantly, but a few had time to go quietly nuts.
Why it is hard sci-fi
Crichtons 1971 procedural about a five-stage underground biocontainment lab handling an extraterrestrial microbe recovered from a crashed satellite. The film walks through every step of the protocol. Sterilisation, level descent, organism characterisation, mutation tracking, and the auto-destruct interlock that fails for a procedural reason. It is one of the cleanest pandemic-procedure films ever made.
Science inside it
BSL-style biocontainment, electron microscopy, crystallography for organism characterisation, pH sensitivity as a containment hint, and the failure of an interlock that is supposed to sterilise the facility on detection of a breach. The films Andromeda organism mutates between metabolic forms in response to environmental stress, which the team works out by elimination.