A student of Dhaka Residential Model College went missing while taking a bath at the Piyain River in Sylhet's Jaflong on Friday.
The student was identified as Al-waz Arash, 15, is a ninth grader at the institution and son of police inspector Zahedul Hossain, a resident of Shidlai village in Brahmanpara upazila of Cumilla.
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According to the tourist police and local sources, Arash along with his parents and younger brother came to Jaflong from Dhaka on Thursday afternoon.
The incident took place around 3:30pm while Arash and his father went to Piyain River to take bath and they drowned.
Later, local people managed to rescue Zahedul but Arash went missing.
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Jaflong tourist police's inspector Md Ratan Sheikh said that rescue operations are being carried out in coordination with police, BGB and fire service personnel.
"The rescue operation will continue until we find him", he added.
Earlier, a 23-year-old tourist, who went missing from Sada Pathor area of Companiganj upazila in Sylhet on Sunday, was found dead after 44 hours on Tuesday.