Amit Shah earlier spoke to the Delhi Commissioner of Police and the Special Branch in-charge, while the NSG and NIA teams are leading a multi-agency probe into the blast.

The force of the explosion that killed 13 people and injured 24this evening near Delhi’s historic Red Fortwas so powerful that the door of a car was flung nearly 100 metres from the blast site, officials said.

Sunday had marked a grim peak, with the AQI climbing to 391 by 10 am – the worst level recorded this season so far.