'We are so far clueless about the Don Group, we have never heard about it, it may be a group of some local criminals or may be linked to Maoist rebels. We are doing the best to make some arrests as the blast occurred just a day before the Ganesh festival and also close to the BJP headquarters. It has also created a scare and raised security concerns,' a senior police officer said, requesting his name be withheld.

The police are planning to step up security at the state's largest Raipur-based government hospital, Dr. Bhimrao Ambedkar Government Hospital, which is the next target of the Don Group according to the slip recovered from the bus.