Was Delhi violence planned well in advance?

Delhi witnessed violent clashes, riots and arson for three days. At least 42 people have lost their lives. But the clashes may not have been spontaneous. From 'petrol bombs' being recovered from the area where clashes took place, to weapons being brandished by rioters in the videos, here are the five clues that indicate that Delhi violence didn't start spontaneously but was planned well in advance.