MOSCOW , Russia ( CNN ) -- Members of a Russian doomsday cult barricaded themselves in a cave to wait out the end of the world as the cult 's leader underwent psychiatric exams Thursday , Russian media reported . The cult , which calls itself the `` true Russian Orthodox Church , '' believes the world will end in May . The cult leader is in police custody awaiting proceedings on charges that he set up an organization `` whose activity is associated with violence on citizens and instigation to refuse to perform their civil duties , '' according to the state-funded Itar-Tass news agency . Four children are among 29 cult members holed up in a ravine in Russia 's Penza region , where they apparently dug a cave . One of the children in the cave is 18 months old , reported Itar-Tass . Temperatures in the cave are below 54 degrees Fahrenheit ( 12 degrees Celsius ) , the Russian news agency reported . The cult members have refused law enforcement requests to come out or release the children , and they have threatened to commit suicide if police resort to force , according to Russian state television . The cult , which calls itself the `` true Russian Orthodox Church , '' believes the end of the world will come in May 2008 . Prosecutors announced Thursday they are opening criminal proceedings against the cult 's leader , Father Pyotr Kuznetsov . Kuznetsov , 43 , is `` under the supervision of investigators , '' Olig Troshin , a Penza prosecutor , told Itar-Tass . A law enforcement source in Penza told the Russian news agency Interfax that Kuznetsov `` is being examined by psychiatrists . '' Several clergymen , police officers and agents of the Russian Ministry for Emergency Situations are outside the cave . `` It is obviously some kind of insanity , '' Mitropolitan Kirill , a high-ranking Russian Orthodox Church official , told Russian television . `` It is perhaps even a medical case . A very dangerous phenomena is happening in Russia 's religious life . '' He added , `` What we 're seeing in Penza right now is a most vivid example of what could happen to a country , to a society , if this society is deprived of proper religious education . '' E-mail to a friend . CNN 's Maxim Tkachenko contributed to this report .
Four children , one 18 months old , are among cult members holed up in cave . Cult leader to face charges he set up a violent organization , news agency reports . News agency : Cult members have threatened to commit suicide if police use force . Score: 6