Two kg explosives used in Delhi blast: Home Ministry

"The explosives quantity is estimated to be about 2 kilograms which created a crater 2 feet wide and one feet deep. It is deduced that most of the casualties have been caused by the blasts (not by shrapnels)," Secretary (Internal Security) in MHA, U K Bansal told reporters.

He said that preliminary forensic investigations reveals that explosives used could be nitrate-based. "Some traces of PTN are also being suspected," Bansal said.
PTN, short for pentaerythritol trinitrate, is a chemical explosive that has a long history of terrorist use.

The official said that the National Investigating Agency (NIA) has taken up the investigation and has deployed a team of 20 officers to go into various aspects of the probe. Bansal said that detailed forensic examination is going on and investigators were trying to ascertain the authenticity of an email sent to certain media houses purportedly by Harkat-ul-Jehadi-Islami (HuJI), a banned terror group, claiming responsibility for the blast.

NIA has also sought Delhi Police help in the investigations. Bansal said Prime Minister Manmohan Singh has announced an ex gratia of Rs two lakh for the next of kin of those killed in the blast and Rs one lakh to the injured.