Lets not jump to conclusions already. Earlier, during the Nirbhaya protests, AAP volunteers were arrested for killing a constable - later it turned out the guy died of a heart attack and the arrested volunteers weren't even there , and were hauled up from random places.
While it's disgusting if AAP folks actually initiated violence (or for that matter even responded to violence with violence. When you agitate, you must be ready for this, and can't end up mimicking what the "run of the mill" political parties do), lets wait a bit before sounding the judgement here.
PS: Kejriwal seems to have apologised, which does suggest some wrongdoing at least (even if retaliatory) from the AAP. But this shouldn't equate them with maoists / naxals - otherwise both BJP & Congress would qualify for the tag to a far greater extent.