It looks like radical Islam has struck again
That's probably not correct in this instance - sorry, what I mean is, although they may be Muslims, religion wasn't the motivation. The most likely perpetrators are rival Chechen militants, who oppose the Russian 'sponsored' government.
Much like the exiled Chechen ex-president who was assassinated in Qatar in February in a car bomb - he had been threatening to return to Chechnya to lead political opposition. Two Russians are current on trial for his murder.
Chechnya is a bloody mess now, and going to get worse following Putin's comment "Retribution is inevitable."
Time flies like an arrow. Fruit flies like a banana!