Indian police raided slums in India's capital today rounding up suspects, after yesterday's multiple bomb attack in the city killed at least 20 people and wounded nearly 100.
Police said they were pursuing several leads, including talking to an 11-year-old boy who said he had seen two men drop off a large plastic bag at one of the blast sites.
At least five bombs exploded in quick succession in crowded markets and streets in the heart of New Delhi.
A group calling itself the Indian Mujahideen (IM) sent an e-mail to television stations shortly after the first explosion saying it was responsible.
The group, believed to be an offshoot of the banned Students' Islamic Movement of India, has sent similar e-mails before or after several major attacks in India in recent months.
"Eye for an eye. The dust will never settle down," the Hindustan Times quoted the e-mail as saying.
"Our intense, accurate and successive attacks ... will continue to punish you even before your earlier wounds have healed," it said, referring to bomb attacks in Indian cities in May and July that together killed more than 120.
"We have detained 10-12 people for further questioning," said Ranjan Bhagat of Delhi Police, adding that no formal arrests had been made.
Police said they were studying footage from close-circuit television cameras at two of the markets hit by bombs.
"We need to see if there is anything in it," said H.G.S. Dhaliwal, a deputy police commissioner. "Hope we find something."
The investigation net widened to the financial capital of Mumbai after it was found the e-mail had originated from there.
"We have located the IP address to a company in Chembur," said an anti-terrorism squad official, referring to a Mumbai suburb. "It looks like a wi-fi connection was hacked into."
Mumbai, which has seen some of India's worst attacks, was also linked to co-ordinated bombings in the western city of Ahmedabad in July after another e-mail was traced to the city.
The Indian Mujahideen has earlier claimed to be avenging the killing of some 2,000 people, mostly Muslims, in a 2002 riot in the western state of Gujarat.
Investigations into bomb attacks in India over the years have followed a familiar pattern. Bombs go off, police round up suspects, usually Muslims, and then the trail goes cold.
Last week, the chief cleric of Delhi's biggest mosque, Maulana Syed Ahmed Bukhari, met Indian Prime Minister Manmohan Singh to complain that innocent Muslims were being arrested "in the name of terrorist activities".
"It should be apparent by now, first, that we have only identified the tip of the Jihadi iceberg," B. Raman, a former head of India's spy agency, the Research and Analysis Wing, wrote in the Hindustan Times.
"The iceberg itself remains unexposed. Second, we have not yet been able to identify the command and control of the IM."
Reuters