According to sources, investigators suspect involvement of the Taliban, particularly the Haqqani group behind the Friday's Feb 26 assault.
Sources said, the attack was carried out in a coordinated manner with the terrorists first exploding bombs and then launching the armed assault.
This was similarly seen in Mumbai during the 26/11 attack, sources said.
About six to eight terrorists are suspected to have been involved in the assault at around 6.30 am at the Park Residence Hotel and adjacent Noor guest house, where Indians on transit usually stay, the sources said.
Indian Ambassador Jayant Prasad said, "The terrorists targeted those Indians who were engaged in helping Afghan people and building partnership between the two countries."
"It is the handiwork of enemies of Afghan people and friendship between people of India and Afghanistan," Prasad said.