A probe is on in the matter, police said, adding no arrests have been made so far.
A group of armed men on Friday barged into a branch of the ICICI Bank in Basti and took away cash of over Rs 20 lakh, police said.
The incident took place about 1 pm when four persons brandishing pistols and donning face masks entered the bank and looted it, senior police officer Hemraj Meena said.
The exact amount of cash looted could not be ascertained yet as bank officials were verifying it, he said.
Sources, however, said that miscreants managed to take away at least over Rs 20 lakh.
A probe is on in the matter, police said, adding no arrests have been made so far.