The secret of the M30A1 lies in a huge number of tungsten BBs arranged around an explosive core – about 182,000 of them. The design is from a technology known as Lethality Enhanced Ordnance developed by Orbital ATK, later acquired by Northrop Grumman. This approach uses computer modeling to calculate the optimum size, number, density and placement of fragments to ensure that a warhead produces the maximum possible effect against a specific type of target. The developers claim that the M30A1 produces the same sort of lethality as the cluster warhead. This blanketed an area of over four football fields per rocket, so a salvo of six would blanket half a square mile.

Imagine riding along, you're suddenly on the floor somehow and everyone is dead or dying around you.

Thats the one! I had forgotten how you could see all the punctures in the windshields. But when not a single tire survives, it indicates a very high density of shrapnel. I saw someone else commenting here that this could have been a Bradley, and while a Bradley could probably also have decimated an unarmoured column like this one, I don't think we would be seeing this kind of damage if that was the case.

The corpses could in principle have been placed there after the strike, or could have been killed by machine gun fire to the back of the truck. To me, what makes HIMARS the likely culprit here is the tires.