The Crazies (1973)

A young girl getting a late night drink is teased by her brother.  Their incipient argument is short-circuited by their father going on a berserk rampage that sees their mother murdered and their home in flames.

Neighbours raise the alarm over the fire, and among the first people contacted are a young couple named Judy and David.  David's a volunteer firefighter called to help battle the blaze.  Judy is a nurse summoned to help look after the injured children.  By the time she gets to the clinic, however, she finds it occupied by the US army.  There's been an accident with some dangerous bio-weapons, you see, and the residents of the town may all have been exposed to a bio-agent that causes either death or a homicidal frenzy in all of its victims.

Now Judy and David and the other folk of the town - as well as the basically well-intentioned but completely out of their depth and overwhelmed members of the military - must try to survive an ever spiraling cycle of suspicion and violence.

The Crazies is written and directed by George Romero of Night of the Living Dead fame, and it shares a fair few similarities with his most famous film.  You've got an outbreak of violence behaviour, a group of ordinary people trying to survive it, and growing tensions among said group as their situation becomes more difficult.  You can also see some of the themes of his later zombie films getting an early work-out here, e.g. the authorities flailing ineffectually to contain the situation, and frequently make things worse as half-trained and barely-informed soldiers are sent to do a dangerous and difficult job with inevitably tragic results.

I also don't think it's a coincidence that old George made a movie about dangerous military chemicals/bio-weapons just a year or two after the US discontinued use of Agent Orange.

I would describe this film as more entertaining than it is good.  Romero was not a subtle film-maker, and this is not a subtle or nuanced film, with performances to match.  It's also afflicted or blessed (depending on your perspective) with an incongruously chirpy soundtrack.  On the other hand, it moves briskly and I was never bored.  If you liked Night of the Living Dead, it's worth checking out what Romero was up to before he finally pulled the trigger on a sequel to that film.