The boat sank near Shah Porir Dwip, the southern-most tip of Bangladesh, at around 3.30 am.
Rohingya Muslims attempting to cross the river into Bangladesh for safety, were on the boat, the reports quoted Government sources as saying.
Bangladeshi coastguards along local residents found bodies of four children and four women from the river that separates Bangladesh from Myanmar.
Many others are believed to have gone missing.
The rescuers found 21 people alive and helped them come ashore.
An estimated 537,000 Rohingya Muslims have reportedly entered Bangladesh since the Myanmar army launched an anti-insurgency crackdown in Rakhine state, according to International Migration Agency.
Nearly 180 Rohingya have drowned while trying to cross the border over the Naf river since the violence began on August 25.
Banner Image: Wallpaper
Rohingya Image: OCHA/Anthony Burke