Chattogram district administration locked down six buildings in the city's Dampara area on Friday night.
At least 80 families live in those buildings, Executive Magistrate of the district administration Mamnun Ahmed Anik told The Business Standard.
Earlier of the night, the port city confirmed its first case of novel coronavirus.
The 67-year-old male is currently in the isolation unit of Chattogram General Hospital.
The Bangladesh Institute of Tropical and Infectious Diseases (BITID) tested 33 people in the port city on Friday. Among them, the old man came positive with the virus.
The BITID started performing coronavirus tests in Chattogram after receiving around 150 coronavirus testing kits from the government on March 26.
Earlier on Friday afternoon, Health Minister Zahid Malik, in a virtual briefing, confirmed five new cases of coronavirus.
With this, the total number of coronavirus patients stands at 61. No new death was reported in the last 24 hours. So far, six people have died from the virus infection in the country.