VLADIVOSTOK/MOSCOW, January 28 (RIA Novosti) – At least eight sailors are presumed dead after a Russian fishing vessel sank in the Sea of Japan on Sunday, possibly because of safety violations, Russian officials said Monday.

Rescuers were still searching for survivors on Monday, while officials from Russia’s Investigative Committee conducted a search at the offices of the ship's Vladivostok-based operator, Vostok-1, as part of a criminal investigation that could lead to charges of maritime safety violations resulting in the death of two or more persons, according to a spokesman for the investigative body.

These charges carry a punishment of up to seven years in prison.

The ship, Chance 101, was carrying 30 crew members, including 19 Russians and 11 Indonesians, before it was discovered overturned off the coast of Russia’s Primorye Territory on Sunday.

Fifteen sailors were found alive aboard two lifeboats, according to emergency ministry officials, while a spokesman from the Investigative Committee said eight others were tossed overboard after they succumbed to hypothermia in the lifeboats. Eleven survivors are Russian, while four are Indonesian.

Meanwhile, several crew members are still missing.

Vostok-1 published the names of the Russian survivors on its official website.

Investigators are currently reviewing two versions of events: the violation of maritime rules by crew members and technical failure. Crew members reportedly told investigators the boat was hit by a wave as it was executing a maneuver.

As of Monday afternoon, air rescuers had combed an area of about 3,000 square miles over the Sea of Japan.

“Unfortunately, the search has not produced any positive results,” the regional branch of Russia’s Emergencies Ministry said in a statement on Monday, after the first 15 survivors had been found. “The search continues.”

The air search, however, was put off until Tuesday morning because of nightfall.

The Prosecutor General's office also said Monday it would review the procedure for the rescue operation, as well as the ship's paperwork and preparedness for ocean travel.