A large crowd had gathered on the bridge in Patuakhali district as desperate people waited for the arrival of relief supplies. The bridge gave way, collapsing into a river.
Saturday's incident strikes a vulnerable population that is still reeling from Cyclone Sidr, which hit Bangladesh more than a week ago. The storm killed more than 3,500 people and displaced at least two million others.
Many survivors face disease and starvation. In some places, people are suffering from water-borne illnesses such as diarrhea, which can be deadly to children.
Adding to hunger concerns, the storm wiped out much of the country's crops and fisheries.
A U.S. Navy ship, USS Kearsarge, has arrived in Bangladesh to assist in relief efforts, with a second ship due to arrive in the next day or two.
The ships are carrying helicopters to deliver much needed supplies to the thousands who have had little access to shelter, food or clean water. The ships will coordinate with the Bangladeshi military.
The Bangladeshi government says it has received nearly $400 million in financial aid from the international community, including $250 million from the World Bank.
Relief workers have set up shelters for the scores of children orphaned by the deadly storm.
Cyclone Sidr is the worst natural disaster in Bangladesh since 1991, when a cyclone and storm surge killed around 143,000 people. - VOA News