Moscow (CNN) -- At least four bodies have been found and 49 people are missing after an offshore drilling rig capsized in the Russian far east Sea of Okhotsk, the Russian Emergency Situations Ministry said Sunday.
At least 14 people were rescued from the rig, which was being towed from Kamchatka, regional Emergency Services spokesman Aleksandr Ivelsky said.
But he insisted that it was too early to declare that the four people spotted in the water without signs of life were dead, since rescuers had not yet recovered the bodies.
There were 67 people aboard the Kolskaya platform, which was subcontracted to a company working for the Russian energy giant Gazprom, state news agency RIA-Novosti reported.
Two ships were on the scene, the icebreaker Magadan and the tugboat Naftogaz-55, and will work on rescue operations through the night, Ivelsky said.
Helicopters were involved in the early phase of the rescue, which was made more difficult by the storm that sank the rig, Ivelsky said. They have stopped flying for the night but will resume work in the morning, he said.
The rig was floating about 124 miles (200 km) from Sakhalin Island, authorities said -- north of Japan and northeast of China.
It was drilling a well about 11,480 feet (3,500 meters) deep, RIA-Novosti said.
Taimuraz Kasayev, a spokesman for the regional emergencies service, told RIA-Novosti the accident poses no environmental danger because the rig's fuel stocks were hermetically sealed and would not spill.
The television channel Russia Today reported that the rig was being towed into position when pumps failed, causing it to take on water and sink.
CNN's Alla Eshchenko and Joseph Netto contributed to this report.