its possible that with an adrenalin rush like that he just pulled his gun and started firing and just thought he was aiming at the car. I remember reading somewhere that people that were not properly trained to use firearms plus handling stressful stituations do all kind of weird things without realizing it. Like trying to insert magazines upside down in weapons, not reloading, forgetting to click off safetys, firing wildly, etc.
I curious to wonder what the driver of the armored truck thought he was doing or trying to accomplish?