Five people, including four children, died as an engine boat carrying them sank in the Turag River on Saturday morning.
The boat capsized when it collided with a sand-laden bulkhead at Amin Bazar in Dhaka.
Two other passengers are believed to have gone missing, she added.
The rescue operation was suspended around 6:00pm due to high current in the river and darkness, she described.
The officer went on saying that Dino Moni Sharma, deputy director (Dhaka Division) of Fire Service and Civil Defence, declared the suspension of rescue operation, which would resume on Sunday morning.
Bangladesh Inland Water Transport Authority (BIWTA), meanwhile, formed a three-member probe committee with its Joint Director Fazlur Rahman as the chief.
The Dharla-4, a crane boat of the BIWTA, brought the sunken boat ashore at about 3:00pm.
After tracing, police would file a case against staffers of it, he said.
Local people and police said that the boat with about 18 passengers left Keblarchar ghat for Dipnagar ghat around 5:30am.
The bulkhead hit it in the mid river. Of the passengers, 11 could swim ashore.