There’s a building on a quiet alley in a rundown part of the city that’s almost abandoned, draped in shadow and disrepair. Inside the building is a collection of individuals from vastly different walks of life. There is a supervising lieutenant freshly assigned to the job. There is a grief-stricken father in the throes of shock after discovering his murdered daughter. There are two dainty secretaries wearing sweaters (one orange, one yellow). There are three hardened criminals, one of whom is sick with a possible virus. Each of the people inside the building is an individual with an individual story. Outside is different. Outside is a creeping evil, a legion of hunters that is nonetheless a single faceless and motiveless mass, no individual stories to be found. The hunt is all.

…sounds like a horror movie, right? Like the kind John Carpenter might make? Even beyond Carpenter, this is not at all an unfamiliar formula for fright-fests — strangers unite against mysterious evil — serving as the entire premise of movies like Cube and Saw. The idea that something lurking out there will inevitably attack each stranger regardless of their differences is an inherently scary notion. And even though Assault on Precinct 13 isn’t necessarily a horror movie, it’s at its most effective when it operates like one.

Carpenter began his feature film career with 1974’s Dark Star, a space-set black comedy which he directed, co-wrote, produced and scored. Assault would follow a similar formula, with Carpenter wearing more than just the director’s hat, but the man himself considers the later film his first “real” venture into cinema. Today, of course, we know Carpenter mainly by association with the horror genre he became so renowned for in the wake of Halloween and The Thing — this is a long way of saying you’d be forgiven for thinking a forced correlation between Assault on Precinct 13 and a horror film might be mere projection. It’s an action movie, or a thriller. Right?

Audiences grappled with this in 1976, too, or at least they might have if anyone turned up to watch the movie. The Wikipedia page for exploitation film claims Assault under the subcategory shocksploitation, which more or less encompasses anything that’s shocking (“positively shocking”). Right under that, not three lines later, Carpenter is credited with jump-starting the slasher genre with Halloween and putting the modern twists on Hitchcock’s Psycho. Still others try to go one step further and class most of Carpenter’s filmography as “cult films”, a term which has admittedly become so sorely misused over the past decade that the power seems sucked out of it (“it’s destined to be a cult classic!” — isn’t that instantly self-defeating?). Assault fits with this description as well because, again, hardly anyone knew it existed in 1976.

The structure of the movie might lead to genre confusion as well, or at least contribute to that felt need to categorize the thing as quickly as possible. Assault begins quietly. Bishop, a cop, is assigned to supervise the final night of a precinct about to close down, so he takes the scenic route and heads over in his prowler. At a prison elsewhere, the smooth-talking Napoleon is cuffed and led out of his cell for transfer to another facility. And elsewhere still, a father and his cute little daughter roam the streets of L.A. looking for Auntie’s house, which dad swears is just up around the corner somewhere. This bonewhite excitement (ahem) continues for a full half hour, which is an eternity to people familiar with the 2005 remake.

At the 30-minute mark is the famous ice cream scene, which remains one of the most shocking (“positively shocking”) movie deaths of the era. Cute little girl wanted vanilla twist, not just vanilla, but the black-garbed man she encounters on her second pass at the ice cream truck isn’t the ice cream man. Out of nowhere this violence descends, transforming the world of hunting for Auntie’s house into a far more dangerous one. Dad, horrified beyond humanity, frantically tears after the gang and confronts them. Gunfire is exchanged. By the 40-minute mark, ten intense minutes after the intensity first woke up, that black-garbed killer is dead. Dad flees in shock and panic as we see a collection of feet gather around the body of the dead man.

That man might be the gang leader, and so the ensuing events of Assault on Precinct 13 (which, for those of you who haven’t seen the film, consists of an assault on the 13th Precinct) might be chalked up to revenge, motive ascribed to pure retaliation. But part of the point of recounting this is to show that these gang members have no names, no voices, and rarely anything more than a shadow between the trees to identify themselves as human. We see the face of that first man and his few cohorts, and we see two more as they approach the precinct. Hundreds more emerge from thin air, appearing as suddenly as that ice cream scene appeared a half-hour in, and they’re never anything but dead silent. Their motive doesn’t feel like revenge or retaliation because their movements are so automatic and practiced. The gang is more like a pride of hunters, terrorizing the prey in the precinct not because their leader is dead but simply because it’s what they do.

The dad doesn’t say much of anything for the rest of the film, either, electing instead to cower under a blanket for the duration of the actual siege. But he still has far more depth than any of the attackers, and we certainly understand his behavior. That’s more than we can say for the gang, and that’s the primary reason why Assault has such success with the horror formula (we wrote about the terror behind this inability to understand something in our recent review of It Follows, too). We don’t necessarily have to shove everything into a category, and in the case of a genre collage like Assault on Precinct 13 it’s probably best that we don’t.