Flagging a sudden rise in Covid cases across 14 cities, the Centre has written to states, urging them to take immediate measures to check the surge. Mumbai saw a massive surge in fresh coronavirus cases yet again today with 3,671 infections - 46% higher compared to yesterday. Election rallies underway in Uttar Pradesh and the violation of distancing norms there are the responsibility of the state government and the Election Commission will take over only after poll dates are announced, Chief Election Commissioner Sushil Chandra said today.