The blast, initially suspected to be due to a gas cylinder explosion, engulfed the entire bakery in flames, trapping many of the victims during the peak weekend business hour.
Pillai said Lashkar-e-Taiba (LeT) operative David Coleman Headley had surveyed the area where the blast occurred but refused to immediately link the attack to any terror organisation.
"The Osho Ashram, situated barely 200 yards from the bakery, was one of the sites surveyed by Lashkar operative David Headley," Pillai said, adding the central agencies had informed the Maharashtra Police on October 12, 2009 about Headley's visit.
Maharashtra Deputy Chief Minister Chhagan Bhujbal said: "We are checking if there were intelligent inputs. We get regular inputs but I do not know how specific they were."
As per preliminary investigations, at least 5-7 kg of explosives were triggered off by an improvised explosive device (IED), similar to the type used in the serial blasts in Mumbai suburban trains almost five years ago.
The injured have been shifted to various public and private hospitals including Sassoon, Ruby, and Jehangir hospitals.
Maharashtra Chief Minister Ashok Chavan said relief and rescue efforts were in full swing.
"It's a unfortunate incident. ATS is investigating. Security has been beefed up at important places. We request people not to panic. Police is doing"its job," he added.
The investigators have not zeroed in on any group or individuals who could be behind the explosion, but the police have detained a cashier of the bakery for questioning and investigations, Pune Joint Police Commissioner R. Sonawane said.
Pillai said a team of forensic experts from the Central Bureau of Investigation (CBI) was being airlifted to Pune to assist the state police in investigations.
"Maharashtra Police, the state's Anti-Terrorism Squad and forensic experts from the state government were at the site to conduct investigations," the home secretary said.
Pillai said that the Maharashtra government had issued an advisory in the wake of the blasts and an advisory had also been issued by the home ministry warning the people not to open any unidentified objects and report all such cases to the police.
Union Home Minister P. Chidambaram, who is currently in Tamil Nadu, is likely to visit Pune Sunday. 'Headley had surveyed area near Pune blast site'
German Bakery is a landmark frequented by the elite and popular with foreigners and has often been compared with the Leopold Caf� in Mumbai, one of the targets in the Nov 26-29, 2008 terror attacks.