Residents of Beslan, the North Caucasus city that saw one of the deadliest school shootings in history some 20 years ago, gathered spontaneously on Saturday to commemorate the victims of the Moscow concert hall attack. More than 1,000 people came together and lit candles for those killed in Friday’s mass shooting at Moscow’s Crocus City Hall, Russia’s TASS news agency reported, adding that the gathering was organized by the Mothers of Beslan group. In what is known as the Beslan school siege, more than 1,100 students, teachers and parents were held hostage by some 30 Islamist terrorists in Sep…