A crude bomb went off in front of the main opposition BNP's central office in the capital's Nayapaltan on Saturday evening.
The incident occurred around 6:10 pm, Paltan Police Station Officer-in-Charge (OC) Salahuddin Mia told UNB.
Some five to six people have been detained from the spot over the incident for questioning.
Additional police force has been deployed in the area to avoid any untoward situation, he said.