Four boat passengers, most of them ethnic Karen, went missing after a long-tailed boat in which they were travelling capsized in the Moei river in Tha Song Yang district of Tak on Monday.
There were seven passengers on the boat, said officials, adding that the vessel capsized because of the strong current in the river which marks the natural border line between Thailand and Myanmar.
Rescue workers from the Petkasen-Tha Song Yang unit were quickly rushed to the scene to search for the missing who were believed to be drowned.
The four missing were identified as Ms Meeplor Satikongsakul, 8-year old Nor Day Day, Ms Taeja Krongkot who was nine months pregnant and 8-year old Nichapat Krongkot.
Source: Thai Public Broadcasting Service (Thai PBS)