The incident took place near the venue of Congress leader Harminder Singh Jassi's roadshow.
Kejriwal blames Sukhbir Badal for blast, while Sukhbir, Amarinder blame the AAP chief for it.
Ruling Shiromani Akali Dal and Congress won one seat each in the bypolls to Patiala (urban) and Talwandi Sabo Assembly seats on Monday but the Aam Aadmi Party finished a poor third.
The step was taken following questioning of another arrested functionary of the sect in connection with an alleged conspiracy to facilitate Dera chief Gurmeet Ram Rahim's escape after he was convicted for raping two disciples, police said.
The Congress vice president also accused Delhi CM of "helping" forces who want to disturb Punjab's peace and push it back to the dark days of militancy.
Congress leader and former union minister Preneet Kaur on Monday won the Patiala assembly seat defeating her nearest Shiromani Akali Dal rival Bhagwan Dass Juneja.
Ram Rahim did not talk with anyone and was seen roaming in the cell.
The high-voltage campaign for the February 4 assembly elections in Punjab came to an end on Thursday evening following hectic campaigning by various political parties.