Correction: 29/09/2017: A previous version of this story identified one of the survivors as Nurul Islam. That was incorrect. His name is Nurul Salam.

Cox's Bazar, Bangladesh - Scores of people, including many women and children, are feared to have drowned when a boat carrying Rohingya fleeing unrest in Myanmar sank off the coast of Bangladesh, police and witnesses have told Al Jazeera.

More than 100 Rohingya were on board the vessel when it capsized in rough seas around 5:30pm (11:30 GMT) on Thursday close to Patuwartek, some 8km off Inani Beach in Cox's Bazar District.

Seventeen survivors were found, along with 15 bodies of women and children, police said.

"The Rohingya [survivors] are saying there were more than 100 on the boat," Inspector Mohamed Kai Kislu told Al Jazeera.

"We fear we will find more bodies," he added.

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Nurul Salam, a 22-year-old survivor from Rathetaung, said he had boarded the boat from Go Zon Dia, a Rohingya village along the Naf river, at 10pm on Wednesday (04:00 GMT on Thursday).

He confirmed that more than 100 people, mostly women and children, were on board the boat. Among them were Islam's mother, wife and infant son, as well as his sister and three children - all feared dead.

"I tried to hold on to my son, but I couldn't," he told Al Jazeera, still shocked and exhausted.

Ambulances, police and firefighters rushed to the scene, as did locals carrying torches to help in the rescue operation.

"There were so many children. I saw six bodies wash up," witness Kullia Mia, who was among those who jumped into the water to try and help save people's lives, told Al Jazeera.

Another witness, Bilaluddin, said the sea was "quite rough" when the boat capsized.

"We saw so many people drowning," the 27-year-old told Al Jazeera.

"I found a two-month-old infant. I couldn't save anyone. I recovered three bodies," Bilaluddin said.

"I don't think we can find survivors, but only dead bodies."

READ MORE: Rohingya mothers and babies - Hungry and traumatised

The incident came as the United Nations said that the number of Rohingya who have fled to neighbouring Bangladesh since violence erupted in Myanmar's Rakhine state on August 25 had exceeded half a million.

"We are dealing with an unprecedented flow of people in terms of numbers," said Peppi Siddiq, project manager at the International Organization for Migration.