There are many different groups in Syria.
This Syrian person seemed more related to Isis/Al Qaeda. It is also easier for them to get away to western countries.

Israel usually bombs some targets. Some months they were doing it every day.
Christian population is bombed every Xmas.

The US usually attacks the strategic places that are used as defense against Isis or against Al Qaeda.
Or they kill the remaining people (like prisoners) after the Isis are moved away with Helis.
You can also see US soldiers guarding the bases of Al Qaeda (Al Nusra).

While it is the same country, the bombings seem unrelated to the shooting.
But it could be, as these people are usually brain washed.

In other places there were shootings in US military bases by Al Qaeda from Saudi Arabia.
You probably did not hear much about that. link