The cause of the blast, which occurred on the ground floor of a three-storey building on a busy street in Dhaka'a Moghbazar area, was not immediately known.
"We have information so far that seven people died in the incident and 50 others have been admitted to hospitals," Shafiqul Islam, Dhaka city police commissioner, told reporters after visiting the scene.
Seven other nearby buildings and three buses were damaged in the explosion, he said.
Television footage showed mangled pillars, broken concrete and glass shards strewn across the street.
(Reporting by Ruma Paul Editing by Gareth Jones)

epa09306336 Firefighters inspect a damaged bus at the scene after an explosion at the Moghbazar area in Dhaka, Bangladesh, 27 June 2021. At least seven people died, according to the Dhaka police commissioner, and scores were injured in an explosion at a building in Dakah's Moghbazar area. The cause has yet to be determined, authorities said. EPA-EFE/MONIRUL ALAM