Perm, location of the nightclub explosion

Vladimir Markin, a spokesman for the Investigative Committee, excluded terrorist act as a possible cause of the incident, saying the blast was triggered by "violation of fire safety rules."

"Most of the victims died of burns and carbon monoxide poisoning. In addition, a stampede occurred at the exit," the RIA Novosti news agency quoted the spokesman as saying.

The RIA Novosti said the explosion was followed by a fire, which had already been under control. However, the Itar-Tass quoted a police source as saying that no fire ensued the explosion.

Perm, location of the nightclub explosion

Russian President Dmitry Medvedev ordered Prime Minister Vladimir Putin, Emergency Situations Minister Sergei Shoigu and Prosecutor-General Yuri Chaika to investigate into the cause of the blast.

Medvedev also asked regional Governor Oleg Chirkunov via phone to report on measures to help those affected, said the RIA Novosti.

A governmental commission was being created by Shoigu, who would fly to the tragedy site along with the health and interior ministers.

A criminal investigation on charges of fire safety breaches, which was personally supervised by Chaika, was underway.

Perm, a city on the Kama River, is the capital of Russia's Perm region.