I lived in St. Petersburg for much of the past year.
Maksidom, click link here, is the Circuit City of St. Petersburg. They have 4 stores but do not plan to move into the Moscow market for some reason. Their main competition is
M-Video which is all over Russia. I know the management at MVideo in Moscow. They are very professional and have Harvard MBAs. After, MVideo, the competition would be Lenta (see http://www.lenta.com), with 5 Hypermarkets in St. Petersburg and also professionally run with western-educated managers...and the German giant Metro (see www.metro.de) which is like Sams Club or Costco. Lenta is more like Sams Club. Maksidom is like Circuit City. I cannot see where the mafia would be involved on behalf of one of those competitors. This is interesting. It is also TERRIFYING because all my friends live there!
Russian media is reporting CS gas and linked to the "business activities" of the owners - "business activities" is usually used in the Russian press when they want to say it's mafia-related but don't have the proof to run with the story. More than likely, someone wanted a cut from MaksiDom (the market), didn't get it, threatened to make them "pay" and did so. The Russians are pretty sure the underground passageway bombing at Pushkin Square in Moscow 5 years ago was a business dispute. Unfortunate.