"It's still heavily raining, and visibility has sharply declined. Roads are all under water," he said.
The rains were the heaviest for over seven years, reports said.
Elsewhere in the country, shops, schools and businesses were closed and residents were left stranded in waist-high waters.
Weather officials said 225mm of rain fell in Chittagong and neighbouring districts on Monday, the highest-ever recorded in a 10-hour period.
The weather office said the annual monsoon, which began on Friday and will last until mid-September, was unusually active under the influence of a sea storm in the Bay of Bengal.
Heavy rains have paralysed much of Bangladesh since Sunday, weather officials said.
"Moderate to very heavy rain with wind gusts up to 50kph or more are likely to batter the country for five more days," a weather department bulletin said.
Large areas along the Bangladesh coast have been submerged under between 0.9 and 1.2 metres of water due to a tidal surge triggered by the storm, officials said.