New Delhi, Sept 15 : Delhi police claimed on Monday to have obtained "vital leads" in the Saturday's serial blasts in the national capital that left 21 dead and over 90 injured.
Delhi police said a suspected Students Islamic Movement of India (SIMI) activist based in Mumbai has emerged as a key suspect along with three from Azamgarh in UP.
It has detained eight people in connection with the blasts, who are being questioned.
When asked about the similarities with the Ahmedabad blasts in July, Delhi police spokesperson Rajan Bhagat said, "we have got vital leads" but declined to give details saying "we will solve the case soon".
He said we are preparing sketches of suspected bombers with the help of five eye-witnesses including a teenage balloon seller, who claimed to have seen those placing packets in the dustbins at Central Park in Connaught Place.
Joint teams of central security agencies and police were questioning the suspects, who are believed to have links with the banned Students Islamic Movement of India (SIMI) outfit.
While two more were also being quizzed, two others detained from Barakhamba Road have been released, the sources said.
Initial probe pointed to a group belonging to western Uttar Pradesh.
Police teams have been sent to neighbouring UP and Rajasthan.
The role of Mumbai-resident Mohammed Subhan Quereshi, suspected SIMI activist, was being probed, according to reports.
Police believe that Quereshi could have hacked the WiFI system in Mumbai to send the terror email to various media houses.
Sources said that Qureshi is believed to have visited New Delhi two weeks back and the two persons detained from Okhla would provide leads about him.
Qureshi has been named as an accused in various terror attacks since 2003.
Sources also said strong similarities were found between the Delhi blasts and the serial explosions in Ahmedabad on 26th July that left 53 dead.
Indian Mujahideen, the group responsible for the serial blasts in Jaipur, Bangalore and Ahmedabad, claimed responsibility for the blasts through an email sent to news organisations around the same time when the explosions occurred.
On Saturday, five bombs went off in less than half an hour. Two of them in the heart of Delhi in Connaught Place, two at the upscale Greater Kailash M-Block market in South Delhi, and one, the most damaging one, in the crowded Ghaffar Market in Karol Bagh.