A major terrorist act has been prevented in the city of Voronezh, about 300km north-east of Moscow. Malefactors prepared an explosion of a residential apartment building in the city centre. The terrorists prepared the explosion in approximately the same way as it was done in Moscow, Buinaksk, and Volgodonsk series of blasts in August 1999, Pavel Bolshunov, regional security services spokesman, is quoted by RIA Novosti as saying. Chechen terrorists are largely believed to have been behind those incidents which claimed hundreds of lives. According to Mr. Bolshunov, the terrorists made a hole in a gas pipe in the basement of the house and placed self-inflammable devices near it. Having examined the explosives, experts say professionals may have been involved here. A tragedy was only avoided thanks to the vigilance of the tenants who promptly rang up the local security agency, Pavel Bolshunov said. Criminal proceedings have been launched in connection with the incident.