Two people were killed and some 102 others were missing after a cruise ship "Bulgaria" carrying 188 sank in Volga river Sunday, the Russian Emergencies Situations Ministry spokeswoman confirmed.

Russian Emergencies Ministry members search for the missing people from a tourist boat that sank on the Volga river in the Tatarstan region July 10, 2011. [Agencies]

The spokeswoman for Emergencies Ministry in Moscow, Irina Andrianova said there were 135 passengers and 47 crew onboard when the double-decker went down.

She said 85 people have been rescued by 21:00 local time (1700 GMT), two of them were hospitalized. All of the rescued were picked up by a passing ship "Arabella."

The double-decker vessel went down some 3 kilometers (2 miles) away from the nearest bank in the giant Kuibyshev reservoir on the Volga River some 450 miles (750 kilometers) east of Moscow, the Tatarstan region emergency ministry said. The depth at the site was 20 meters (65.62 feet), it said.

Some 30 children gathered in one of the cockpits minutes before the sinking, another survivor told the Interfax news agency.

Emergency teams and divers from neighboring regions rushed to the site of the tragedy, and Tatarstan's leader Rustam Minnikhanov interrupted his vacation to return to the region.

Andrianova confirmed that there were 148 passengers, 22 crew members, and 16 other staff aboard the double-decker ship, another two people were taken aboard without consent from the tourism company.

Andrianova added that the cause of the sinking was still unknown.

Earlier, a regional Emergencies Situations Ministry spokesman said that there were a total of 173 people aboard the ship, 167 of them had been rescued, but later he said he had been mistaken and that some 80 were safe.

The Kremlin press office said Russian President Dmitry Medvedev has held phone conversation with Emergencies Situation minister after the accident and ordered an investigation into the accident.

The president also ordered Tatarstan head Rustam Minnikhanov to give assistance to the survivors and victims and their families.

The boat, called Bulgaria, was built in 1955 in Czechoslovakia and belongs to a local tourism company. It was going to the regional capital, Kazan from the town of Bulgar.

According to local media reports, three factors may have caused the accident, including the violation of ship's operation, overload, and aging of the ship.

"It case of an accident these ships sink within minutes," Dmitri Voropayev, head of the Samara Travel company told the Ria Novosti news agency.