Four people are being held in jail pending an investigation into a nightclub fire that killed at least 112 people in Russia's worst blaze in decades, investigators said.
About 130 remained in hospital, many in critical condition, with injuries from the blaze, which witnesses said was sparked by on-stage fireworks that shot into the decorative twig ceiling of the Lame Horse club in the Ural Mountains industrial city of Perm.
Shocked and grieving relatives have begun to bury the victims of the disaster.
The federal Investigative Committee said the suspects - the club's owner, the executive director, the artistic director and a businessman hired to install pyrotechnics on the night of the blaze - were ordered to be taken into custody by Leninsky District Court.
The committee's website said they were suspected of negligence causing multiple deaths and violating fire safety rules causing multiple deaths.
Russian news agencies named the owner as Anatoly Zak. The pyrotechnics expert was named as Sergei Dergunov by his lawyer, Yekaterina Golysheva.
Mourning residents were indignant over the alleged negligence, which President Dmitry Medvedev also criticised in a nationally televised video-conference.
Emergency Situations Minister Sergei Shoigu said that the club managers had been fined twice in the past for breaking 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.
Many victims were trapped in a panicked crush for the exit as they attempted to escape the flames and thick black smoke.