MOSCOW - An explosion apparently caused by pyrotechnics tore through a nightclub in the Russian city of Perm early Saturday, killing more than 100 people, according to emergency officials quoted by state television. It was not immediately clear if the pyrotechnics were kept in storage at the club or being used as part of a show like in the fire that killed 100 people at a rock club in Rhode Island in 2003. In the chaotic aftermath of the blast and subsequent fire, casualty figures differed. State television news channel Vesti cited the Investigative Committee, Russia's top investigative body, as saying the death toll was higher than 100. Reports citing other officials ranged from 86 to more than 90.