Maharashtra chief minister Prithviraj Chavan said on Friday that investigators are examining forensic evidence and footage from closed circuit televisions for clues about the triple bomb blasts that shook Mumbai and killed 17.
Chavan told CNN-IBN news channel that investigators had collected "enough" evidence such as blood samples and explosive materials from the bombing sites and were also analysing security footage for more clues into the attacks.
There were fears that the torrential downpours that have hit Mumbai since the rush-hour blasts on Wednesday evening may hamper the probe, washing away vital forensic clues.
Investigation agencies are scanning 11 CDs of CCTV footage for clues into the Mumbai serial bombings, home secretary RK Singh said on Friday.
"There are about 11 CDs (of CCTV footage) which have to be gone through, so it's a voluminous work. People who are not recognised by local people have to be put through a data base... the suspicious people are being verified," Singh told reporters.
"We also have identified the scooter in which one of the bombs was planted. There are various leads based on our previous databases, various people are being questioned, so investigation is going on," he added.
Forensic examination of debris has already indicated that the bombs, hidden in the crowded streets, used ammonium nitrate, a fertiliser ingredient commonly used in improvised explosive devices (IEDs).
No one has claimed responsibility for Wednesday's attacks and investigators have named no immediate suspects.The bombings were the worst terror attack in Mumbai since a 2008 siege in which 166 people were killed over three days.