Four people including three Chinese faculty members of Karachi University’s Institute of Confucius Studies were killed Tuesday when a female suicide bomber targeted the van carrying them.
The investigators believe that the highly explosive C4 plastic explosive materials were used in the attack.
However, the confirmation could only come once ballistics laboratory tests are back.
The investigators said that terrorists used C4 with a mixture of nitrate, sulphur or fertiliser in some cases to ignite fire.
This is what seems to have happened in the Confucius Institute attack. The CCTV footage shows that soon after the blast, a fire broke out in the van. The fire was so intense that it not only destroyed the van completely but also charred the motorcycle of the Rangers personnel escorting the Chinese nationals.
The bodies of the foreign faculty members were burnt beyond recognition and the DNA samples have been taken to identify them.
During a visit to the crime scene, it was observed that a tree at the site had turned black after it caught fire following the blast.
A team of the Bomb Disposal Unit (BDU) visited the crime scene and collected evidence. According to a BDU report, three to four kilogram of explosive material was used in the attack. It also contained metal ball bearings to make the blast more lethal.
Counter-Terrorism Department’s Transnational Terrorists Intelligence Group Chief Raja Umar Khattab told SAMAA Digital that either C4 type or RDX was used in the blast. It is more plausible that a type of C4 explosive was used, he said.
History of terrorists using C4 explosive in Pakistan
December 2009 - Ashura attack
The last known case of C4 use was in December 2009 when a suicide bomber targeted Ashura procession in Karachi. 33 people were killed in the attack.
April 2006 - Nishtar Park blast
As many as 50 people, including several religious leaders, were killed and over 100 others when a bomb went off during a 12th Rabiul Awwal congregation at Karachi's Nishtar Park on April 12, 2006.
March 2006 - US Consulate bombing
Four people including a US diplomat and his driver were killed in a suicide attack outside the US Consulate in Karachi. C4 explosives were used in the bombing.
May 2005 - Imanbargah Madinatul Ilm suicide attack
C4 explosives were used in the 2005 suicide attack targeting Imambargah Madinatul Ilm in Gulshan-e-Iqbal area of Karachi.
December 2003 - Gen Musharraf's convoy
Similar explosives were used in an attempted attack against then-President General Pervez Musharraf in Rawalpindi. A bomb was planted under Chichi Jhanda Bridge to target him, however, it didn’t go off as Musharraf’s convoy had jammers.
History of RDX, TNT use in Pakistan
September 2008 - Marriot Hotel blast
Around 40 people were killed and 250 were injured after a suicide bomber rammed a dumper truck laden with explosives into the Marriot Hotel in Islamabad. Then minister of state on interior Rehman Malik said a mix of RDX and TNT was used in the attack.
October 18, 2007 - Karsaz attack
Around 12kg of plastic explosive and RDX was used in the October 18, 2007 attack on Sharae Faisal Karachi, targeting the motorcade of former prime minister Benazir Bhutto, who was returning from self-imposed exile. A total of 180 people died in the attack.