A Russian double-deck cruise cruise ship that sank in Volga River on Sunday claimed more than 100 lives, with several people still missing.

On Sunday, the cruise ship Bulgaria sailing Bolgary-Kazan sank at 01:58 PM Moscow time (09:58 GMT) in Volga River near village Syukeevo of Kamsko-Ustyinsky district of the Republic of Tatarstan.

According to preliminary data, there were 185 people on board, 148 of them were tourists.  But, according to the officials, only 120 people should have been carried in such vessel.

However, the ship was carrying 196 people instead of the maximum 120 allowed as per the safety rules, President of Tatarstan Republic Rustam Minnikhanov said on Monday.

One hundred and ninety six people were on board. Fifteen people were not on the list as they did not buy tickets, Minnikhanov added.

Media reports in Russia say rescue divers have found more than 100 bodies in the hull of a cruise ship, which went down in about 20 metres of water. Survivors say the ship rolled on its right side and sank in eight minutes on a wide section of the Volga River about 800 kilometres east of Moscow.

Search-and-rescue operation is being carried out at the accident site.

Russia's Ministry of Emergency Situations said 223 people, 37 units of equipment, including 105 people and 15 units of equipment, among them 80 divers and 2 air vessels are working at the site.

Meanwhile, a criminal investigation has begun probe into the accident.

Alexander Bastrykin, the head of Investigative Committee in Russia, arrived at the crash site to organize and coordinate investigations.

Investigators have begun examining the documents seized from the company Argorechtur, which owns the sunken ship. Investigators are also questioning victims and other witnesses at the site, the committee said in a statement.

Here are some heart rendering photos of the tragedy: