PERM, Russia - President Dmitry A. Medvedev demanded yesterday that Russia tighten its notoriously lax fire codes after the deadliest blaze since the Soviet era killed at least 107 people celebrating in a nightclub with a single exit.

About 130 people were injured, dozens critically, when onstage fireworks set the decorative twig ceiling of the Lame Horse nightclub ablaze soon after midnight, witnesses and officials said. Many victims were trapped in a panicked crush for the exit as they tried to escape the flames and thick black smoke.

Officials said club managers had ignored repeated demands from authorities to change the interior to comply with fire-safety standards. Emergency Situations Minister Sergei Shoigu told Medvedev by videoconference from Perm that club managers violated the law by running the fireworks display.

He said the managers had been fined twice before for violating fire-safety regulations, which he did not specify. Russian clubs and restaurants often cover ceilings with plastic insulation and a layer of willow twigs to create a rustic look, one of many uses of combustible materials in buildings by businessmen who bribe officials to look the other way.

The Lame Horse's managers had been scheduled before the fire to report tomorrow on their progress in fixing the flaws.

"They have neither brains, nor conscience," Medvedev said. "They must face the maximum punishment."

He declared a national day of mourning tomorrow.

Authorities quickly arrested two registered co-owners of the club, its managing director, and two other suspects. One other suspect was injured in the fire and remains in critical condition.

Medvedev demanded that lawmakers draft changes to toughen the criminal punishment for failing to comply with fire-safety standards.

Enforcement of such standards is infamously poor in Russia, and there have been several catastrophic blazes at drug-treatment facilities, nursing homes, apartment buildings, and nightclubs in recent years. The nation records up to 18,000 fire deaths a year, several times the per-capita rate in the United States and other Western countries.

Gennady Gudkov, a senior member of the Kremlin-controlled lower house of parliament, said toughening the punishment would not solve the problem. He told the ITAR-TASS news agency that many fire-safety officials are corrupt and often turn a blind eye to violations in exchange for money.

Leonid Miroshnichenko, who lost his daughter in the fire, said he believed the ceiling of twigs and plastic sheeting contributed to the death toll.

"I would like to see the official who allowed this club to open. It was he who killed my daughter," he said.

Video recorded by a witness that was broadcast on Russian television showed people dancing before sparks from pyrotechnic fountains on stage ignited the ceiling around midnight. Witness Svetlana Kuvshinova said the blaze swiftly consumed the twigs.

"People were having fun, and it was the peak of the fun when I looked up and saw flames on the ceiling," Kuvshinova said. "The fire took seconds to spread. It was like a dry haystack."

The footage showed the fire spreading through what appeared to be willow twigs as a host shouted without urgency: "Ladies and gentlemen, guests of the club, we are on fire. Please leave the hall."

"There was only one way out," Kuvshinova said. "They nearly stampeded me."

The video showed people reluctantly heading toward the exit, some still holding their drinks and turning back to look at the burning ceiling. Within seconds they started rushing in panic as flames spread through the hall like a fireball.