That was a military convoy with a remote detonated roadside IED. IEDs aren't just a bunch of explosives wired up. These things can be very intricate and very powerful. I once had a pile of scrap that measured 4x4 feet with assorted parts that was once a humvee with three Marines in it. The only things left of them were teeth.

Most likely this IED was an undetonated warhead that they managed to arm. (Lead truck looked like a 5 or 7 ton truck followed by a Hummer)

Now when I get home I'm going to have a stiff drink and think of my fallen friends.