JAIPUR, India Police probed on Thursday whether Indian Islamist groups or Bangladeshi infiltrators were behind bombings in Jaipur that killed 61 people this week, but made no major arrests.
Eight bombs, many strapped to bicycles, ripped through a crowded shopping area in the city on Tuesday evening and injured another 216 people.
Police said the attack bore some hallmarks of the Bangladeshi militant group Harkat-ul-Jihad al Islami (HuJI), and released a sketch of a man in his mid-20s seen near the scene of one bombing speaking Bengali, the main language of Bangladesh.
An email to local media, from a group calling itself the Indian Mujahideen, declared open war on India and threatened more attacks on tourists. The email also included a video of a bicycle with a bag strapped to it, with the bike's serial number.
"We are looking at various angles, verifying every claim and questioning lots of people," Pankaj Singh, a senior police officer in Jaipur, said. He added that no arrests had been made.
Vasundhara Raje, Chief Minister of Rajasthan, said she doubted the authenticity of the video, echoing comments from other police officials.
"The email was sent to mislead us and the investigation," Raje told reporters.
India has suffered a wave of bombings in recent years, with targets ranging from mosques and Hindu temples to trains. But it is unusual for any group to claim responsibility for attacks.
Islamist militant groups in Pakistan and Bangladesh intent on fanning hatred between Muslims and Hindus in India, and damaging a fragile peace process between New Delhi and Islamabad, are often blamed for bomb attacks in India.
In Jaipur, dozens of Bangladeshi migrant labourers were taken in for questioning. HuJI was blamed for blasts in Uttar Pradesh and Hyderabad last year that killed scores of people.
Bangladesh High Commissioner Liaquat Ali Choudhury told local television on Thursday that he would not make any comments about allegations that HuJI was involved.
The streets inside the walled-city of Jaipur were deserted on Thursday as authorities imposed a curfew for a second consecutive day in some areas.
Many people inside the old city, also known as the pink city because of the colour of buildings, said they were having sleepless nights.
"The sight of human flesh and my injured teenage son lying in a pool of blood still gives me nightmares," Sahid Akhtar, a shop owner in the main square, told Reuters.
In the past few years, bomb blasts in Indian cities have killed hundreds of people. The deadliest was in July 2006, when seven bombs on Mumbai's rail network killed more than 180 people.