If they are 'freedom fighters' why do they terrorize their people? Or maybe because the 'Syrian Armed Opposition' the USA created are not Syrians in their majority? How would you feel if another country created such groups in your city who started blowing up your lives?
This is one of hundreds of such ugly crimes each US citizen - voter and taxpayer is accomplice in, same goes for each citizen and taxpayer of each NATO member state country. Ignorance is not an excuse. You voted for those criminal politicians and you didn't hold them accountable, your tax money instead of spending it for your welfare you preferred to spend it for the destruction of lives of other people on the other side of the planet and you claim you live in a free country with democracy and want to export your way of life to others, by force and by terror.
More about this in this report: Al-Qaeda FSA Detonates a Car in Mazzeh, Damascus.