It took just 10-12 minutes for robbers to loot cash from the bank branch, which had no security guard, police said.
The robbers, whose faces were covered, came on three bikes today at around 2 pm, police said.
One person stood outside the branch to keep a watch while the rest of them looted cash, according to an official.
There were only two bank employees at the time of incident, police said.
Two women customers were locked inside the bank's currency chest room.
The role of an insider is suspected as the robbers reached the bank within 10 minutes of the arrival of cash in the branch, a senior police officer said.
They were carrying two or three 12 bore rifles, police officials said adding that no shot was fired.
They came to the bank within 10 minutes of cash arrival, Muktsar SSP Sushil Kumar said.
Robbers also took away the CCTV footage, according to the police.
Muktsar SP Baljeet Singh said a man hunt has been launched with check points being set up at various places to nab the accused.
This incident came close on the heels of daring robbery that took place yesterday in which armed men looted Rs 1.33 crore from a van belonging to a private bank on a busy highway in Banur near Rajpura town in Patiala district.