According to sources, the suspects could have possibly fled in the car after the blast. Police also claim that a fake registration number could have used been used in the case.
"We have a registration number which we think is fake," said a senior police official.
The blast that shook the national capital on Sept 7, left dozens injured and 11 dead. Hours after the blast, terror group HuJI claimed responsibility for the blast.
The probe into the matter has been handed over to the NIA.
Meanwhile, sources claim that the e-mail sent by HuJI has been traced back to Jammu and Kashmir. The authenticity of the mail is also being verified.
Sources also claim that an internet cafe owner in J&K was interrogated after there were reports that the e-mail was sent from his cafe.