"There has been no arrest or detention so far. We are collecting scientific evidence in the ongoing investigations", Joint Commissioner of police Sanjiv Singhal told reporters.
Amid reports that Indian Mujahideen, which was behind 2010 German Bakery blast here that claimed 17 lives, could have triggered the serial blasts, the officer refused to confirm whether the home-grown terror outfit was involved in the quadruple explosions.
"We will be able to tell only after investigations are complete. It will not be proper to make a comment at this stage," Singhal said when asked whether the blasts carried the stamp of a terrorist network.
Maharashtra Home Minister R R Patil, who visited the four blast sites earlier in the day also said investigating agencies were probing all angles to determine whether any terror outfit was behind the low-intensity blasts.
"Whether it was a terrorist act or not will be determined only after proper investigations are carried out by Maharashtra ATS, city crime branch and central agencies," he said.
"All angles are being probed and it will not be proper to comment at this stage," he said when asked if there could be a "saffron terror" angle to the blasts.
He said few days after the murder of terror suspect Qateel Siddique in Yerwada prison, Pune police had got a letter in Marathi which threatened that the murder would be avenged. "This angle is being probed," Patil said.
Suspected Indian Mujahideen operative Mohammad Qateel Siddiqui was lodged in Yerwada Central Jail for his alleged role in in the German Bakery blast and the Bangalore terror attacks.
He was found murdered in his prison cell in June this year after a brawl with some fellow inmates.
Patil said there were no inputs from central agencies about the blasts.
Singhal said the sole person injured in the blast near Bal Gandharva theatre, the 33-year-old Dayanand Patil was being "interrogated". His wife Satyakala and some bicycle shop owners in the city's Kasaba peth area were also questioned as part of the investigations. More