Police and intelligence agencies are in a tizzy but so far have no leads. In fact many people in the area did not notice anything unusual: they thought the sound was of a car tyre bursting, which did happen, but as a result of nails from the bomb.

A policeman, however, suspected that the sound was of bombs going off and alerted higher-ups. As recently as January 16 a blast had taken place in the vicinity, near the IIT flyover, and very close to the Lado Sarai petrol pump near the scene of Thursday night's blast.

“There was a loud sound then some pellets of the explosive material hit a Toyota Corolla car passing by on the road due to which one of its tyre burst and a nail hit its petrol tank. Some pellets also damaged the right side of the car,” said an officer.

The blasts took place on Anuvrat Marg, near Lado Sarai and Malviya Nagar crossing around 10.30 pm.

The windowpanes of a Wagon R car and a Tavera car broke into pieces due to the impact of the collision. The Tavera car belonged to a Gurgaon based call centre and five employees were inside it, all of them escaped unhurt.

A man driving an Indica car received a head injury after a nail hit on his head, said the police. He received minor injuries and refused to undergo a medical examination, said an officer. All of them have been made witness to the incident.

Police teams and bomb squads recovered nails and chemicals from the spot. They have been sent for forensic tests. Both the blasts took place within 50 meters of each other, police said.

“I was on my way back home at that time. I did not notice anything amiss until I saw that my petrol tank had emptied. I got down and saw that one of the pellets had hit the petrol tank and the other had pierced the tyre that went flat,” said A K Jain of New Friends Colony, in his complaint. He was driving the Toyota Corolla.

Another person, Manish Gupta, a resident of Lado Sarai said, “We thought it was a bomb. I saw people screaming inside the vehicles but nobody was injured.”

Police say that the explosion seems to be the handiwork of some maniac but are not ruling out the involvement of an organised groups.