MOSCOW - Russia vowed Thursday to continue searching a vast area of the frigid Sea of Okhotsk for 13 people missing after a fishing trawler sank, killing at least 56 of the 132 people onboard.
An additional 63 were found alive in the icy waters off the Kamchatka Peninsula in Russia's Far East, but the likelihood of finding other survivors appeared tiny, given the harsh conditions.
Russia's Investigative Committee has begun a probe into possible charges over safety violations in the early Thursday sinking of the Dalny Vostok, which went down in only about 15 minutes.
The emergencies ministry said the area being searched spanned about 3,500 square miles.
Rescued crew members reported that the ship was unstable because of empty fuel tanks and a lack of ballast, and tipped over when a fishing net weighing 80 tons was pulled in, said Oleg Kozhemyako, acting governor of the nearby Sakhalin region.
Kozhemyako's comments on Russian television came after the federal Investigative Committee said it was considering all possible causes of the sinking, including the 330-foot trawler hitting an object floating in the sea, possibly drifting ice.
Those saved had managed to get into lifeboats and some had put on wetsuits, rescue workers said.
The Dalny Vostok didn't send a distress signal.
Video of the rescue operation broadcast on state television showed clear skies and relatively calm seas. The water temperature was near freezing.
Among the people on board, 78 were from Russia, 42 from Myanmar and the rest were from Latvia, Ukraine and Vanuatu.
The Dalny Vostok, which was built in 1989, was equipped to freeze and can fish.