Singh said besides the Prime Minister, Home Minister Sushil Kumar Shinde had also spoken to the Chief Minister.
Four persons have been detained from different areas of Patna and are being questioned by police, according to Patna SSP Manu Maharaj.
Goswami said the Centre will give all assistance to the Bihar government. He said it was up to the state government to decide on what kind of arrangements were to be made for the rally.