The attack follows the shooting and wounding of an Italian doctor working in the same region last month, and the earlier murders of an Italian and a Japanese citizen in separate attacks claimed by Islamic State.
The latest incident occurred in Dinajpur district, 415 km (260 miles) north of the capital Dhaka when a series of bombs exploded as hundreds of devotees attended a religious ceremony known as “Rushmela”, Abdul Mazid, the officer in-charge of Kahalur police station, told Reuters.
The attack came after recent threats to the temple’s priest, urging him not to organise any religious gatherings, Mazid said.
Five people had been detained for interrogation, he said.
Bomb attacks on Hindu religious gatherings are rare in Muslim-majority Bangladesh.
The country has suffered a rising tide of Islamist violence over the past year. Four online critics of religious militancy have been hacked to death, among them a U.S. citizen of Bangladesh origin.