On the first day of the three-day blockade called by BNP-Jamaat, a cocktail explosion took place in the capital's Matuail area.
The incident took place near KF Supermarket in Matuail on Tuesday morning.
Three policemen were injured in the blast.
Police have so far detained 32 BNP leaders and activists.
Their identities have not yet been confirmed yet.
Inspector (Investigation) of Demra police station Farouk said he was one of the injured in the cocktail blast.
“They exploded a lot of cocktails. At least four to five exploded in front of us. Three of our policemen were injured in the incident,” he added.
Witnesses said the blast took place during a police chase with a group of protesters.
