"The incident took place around 00.45 AM WIB (UTC + 7)," East Kotawaringin Police Chief Adjunct Senior Commissioner Himawan Bayu Aji said on Saturday.
Two of the missing Indonesians have been identified as Zulkipli, the tugs captain and crew member Heri Kusmiran. The tug boat was owned by PT Sarmiento Parakantja Timber (Sarpatim) and was used for log barging.
There were three people aboard the tug boat. Two are missing and one person named Nuryadin managed to escape.
"The tug boat had just finished unloading cargo at sea and was to return to the Mentaya waters, when it was hit by a wave," Dodi Wiwoho, an officer from PT Sarpatim, revealed.
A team from the East Kotawaringin water police is conducting a search for the missing crew members.
(Reporting by Untung Setiawan/INE/KR-BSR/F001)