Police in New Delhi hunted Sunday for two suspects involved in the bombing at a city market as the death toll rose to three with two more people dying overnight, officials and news reports said.
Police said two men on a motorcycle and wearing helmets dropped a black plastic bag containing the explosive in the market in southern Mehrauli area on Saturday afternoon, reported dpa.
A 13-year-old boy who had picked up the bag to give it back to the bikers died on the scene as the bomb exploded moments after. At least 22 injured were moved to the All India Institute of Medical Sciences.
"We are carrying on searches for the bombers and extensive checking and raids are being conducted across Delhi to arrest them," Ajay Kashyap, Joint Commissioner, Delhi Police told reporters.
In a related development, the NDTV network reported that the first arrest was made in the case when police held a suspect from the Delhi suburb of Faridabad whose cellular SIM card was used to make calls threatening further bomb blasts.
The report added that several people were detained from the city's southern Sangam Vihar area and were being questioned in connection with the blasts.
A 60-year-old man and another unidentified man succumbed to their injuries overnight, AIIMS hospital superintendent John Bera told the PTI news agency. Six other victims were described as "critical."
The city was on high alert after the Mehrauli blast which came exactly two weeks after the Indian capital was rocked by five synchronized bombings which claimed 24 lives.
But the police did not suspect the Islamist Indian Mujahideen which claimed responsibility for multiple blasts in Delhi on September 13 as well as earlier bombings in the Ahmedabad and Jaipur cities which claimed over 140 lives.
No militant outfit has claimed responsibility for the attack. Investigators said the explosives used were very different from those in the earlier blasts.
The explosion came as Indian cities were gearing up for Eid al-Fitr festivities marking the end of the Muslim holy month of Ramadan and Hindu festival of lights Diwali next month.
"The city remains on alert and police are keeping tight vigil. Checking has been increased at important points. Security has been strengthened at important locations in Delhi," senior Delhi police official HGS Dhaliwal said.