The Jahangirpuri violence was pre-planned by prime accused Mohammed Ansar Sheikh, said sources in the Delhi Police's Crime Branch, which is probing the case.
Seven days before the April 16 Hanuman Jayanti procession, a meeting was organized by Ansar to carry out the attack, sources said on Friday.
The sources privy to the investigation said Ansar held the meeting at Kushal Chowk in Jahangirpuri with 30 people in which it was planned as to how they would stop the procession.
"Red colour stones were assembled by the accused at the rooftop of several houses. It was all pre-planned. The accused later washed the whole roof. It was done in a bid to destroy the evidence," said the source.
The source said that around 30 people attended the meeting called by Ansar.
The meeting was attended by a few juveniles also, said sources.
The sources also said that the accused were talking on Whatsapp calls to avoid recording.
Police are now trying to establish the identity of the accused.
Suresh, who was pulling the procession cart, said that Ansar was leading the protest and was also provoking the mob against them. He said Ansar pushed him and asked him to stop the procession.
The Crime Branch has also scanned dump data of the 10,000 numbers which were active in the area at the time of attack.
Northwest Delhi's Jahangirpuri witnessed violent clashes during a Hanuman Jayanti procession on April 16. Delhi Police have arrested 22 people in the case so far.