A speeding car, bulling through a security checkpoint...
Chalk it up to: 'These things happen'.
Of course, it's probably an armored vehicle, but hearing those rounds hitting the sheetmetal like hailstones and seeing those bullet-proof windows cratering might have induced a coronary...
No, they need the Guard there with a hummer with an M60 on top. Running down a cop at an airport checkpoint is an act of war nowadays, and the entire convoy should have been brought under fire.
And for the bigger airports, a Bradley with its 25mm chain gun would not be out of the question.