Home ministry officials said the nature of explosives used in the blast was not known immediately and the post-blast investigative teams of the NIA and NSG have picked up leads from the spot.
All states have been asked to take precautionary measures and step up vigil in the wake of the blast in the national capital, the officials said.
The explosive device was suspected to have been kept in a suitcase outside the high court compound between Gate No. 4 and 5 and went off at around 10.15 AM when 100 to 200 litigants were waiting to get passes to enter the premises. Some lawyers were also present at that time.
Condemning the “terrorist attack”, home minister P Chidambaram said the probe into the second bomb blast outside Delhi high court in four months has been handed over to the National Investigative Agency (NIA).