A little-known militant group called the Indian Mujahideen claimed responsibility for setting off bombs in the western Indian city of Jaipur that killed 61 people and injured 216 people this week, police said.
A video clip sent by email to national media showed one packet strapped on the back of a bicycle. The email said that the packet contained a bomb, police said.
The video was broadcast on national television channels. Indian media also said the video showed a serial number of one of the bicycles.
"We are examining the authenticity of the video and the claim at the moment," Pankaj Singh, a senior police officer, told Reuters in Jaipur.
Eight bombs, many strapped to bicycles, ripped through the bustling streets of Jaipur on Tuesday evening.
India has suffered a wave of bombings in recent years, with targets ranging from mosques to Hindu temples. But it is unusual for any group to claim responsibility for attacks.
On Wednesday evening, police released a sketch of a man in his mid-20s suspected of being involved in the bombings. Witnesses who helped prepare the sketch told police that the man was seen near the scene of one the bombings and spoke Bengali.
Islamist militant groups in both 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 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 railways killed more than 180 people.
