Mumbai Police suspect that deadly RDX explosive may have been used in the seven serial blasts that ripped through suburban trains during evening rush hour on Tuesday killing 190 people and injuring over 600.
Police sources said the possibility is being explored in the backdrop of the Anti Terrorists Squad's (ATS) seizure of 43 kg of RDX from Aurangabad and other parts of Marathwada and north Maharashtra in the past few months.
"More RDX consignment could still be hidden in Mumbai or around and the same may have been used in yesterday's blasts," a Mumbai police officer said.
The samples from the blast-hit trains have been sent for forensic examination and experts said it would take some more time to reach a definite conclusion.
But the likelihood that compacted low-intensity explosive may have been used has not been eliminated completely.
While Police Commissioner AN Roy could not be contacted for a response, ATS chief KP Raghuvanshi told PTI that, "It was too premature to comment on the issue."
A senior Mumbai crime branch officer said that there was a definite pattern in the blasts and the entire operation was executed with a great precision.
Preliminary investigations have revealed that the explosions were probably timed for 6.15 pm on Tuesday and that the devices might have been loaded at Churchgate station, police sources said.