Well.... jet engines are VERY temperamental. The smallest object can break a turbine fan and everything comes to a halt. Fuel lines can be broken too and that includes ducts to allow the exhaust gas to pass through and escape the engine, if these very high temps can't escape it can cause a failure of the engine. That includes a 5.45mm, granted , that could've been a very lucky shot! :)
At 1:54 sec you'll see what happens when a fan breaks in a turbine engine. :smartass: