Several reports have come out about the two aircraft that were ordered to fire on Libyan civilians but ended up disobeying orders and flying to Malta. Those two jets are reported as F1 Mirages, which were designed as air superiority and attack aircraft for the French military in the 70's.
Standard armament includes two DEFA 553 cannon that fire 30mm rounds (about six inches long) and hardpoints that can hold a payload of bombs, rockets, or missiles. The jets at Malta appear to have been loaded with rocket pods for maximum air to ground destructive capabilities.
These weapons are designed to penetrate targets with significant armor, like tanks. Meanwhile the protesters that were to be fired upon had the armor capacity of, well, whatever a t-shirt does to stop bullets and rockets. It's also worth nothing that these weapons, in a crowd context, are for indiscriminate slaughter, not for hitting individual targets.