Investigators were examining security camera footage for clues to the Mumbai triple bomb blasts that killed 17 people, officials and media reports said Friday, dpa reported. Federal Home Minister Palaniappan Chidambaram said there were no immediate leads on who was behind the bombings that rocked India's financial hub during the evening rush hour on Wednesday. A total of 134 people were wounded in the blasts at the Zaveri Bazaar jewellery market and the Opera House business district in southern Mumbai and the crowded neighbourhood of Dadar in central Mumbai. Home Secretary RK Singh said that footage from security cameras at all three blast sites was being scrutinized by investigators. Of particular interest was the footage at the Opera House area which showed four men speaking on their phones for 90 minutes, official sources told the NDTV network. Investigators were trying to establish their identities, the report said. Forensic evidence such as blood samples and explosive materials had also been collected from the sites. Officials said the bombs contained ammonium nitrate, TNT and fuel oil. They were triggered, most likely, by cellphones. No militant group claimed responsibility for the attacks and the police have not made any arrests in the case. -- SPA