A fire broke out in a women's ward of a Moscow drug treatment hospital early Saturday, filling the ward with heavy smoke and killing 42 people, the city fire department said. Russia's chief fire inspector, Yuri Nenashev, said he was "90 percent certain" that the fire was caused by arson. But Moscow city prosecutor Yuri Syomin said that investigators were looking into other possibilities, the ITAR-Tass news agency reported. Moscow fire department spokesman Yevgeny Bobylyov said that investigators were still working at the site of Hospital No. 17 in southern Moscow but that it was already clear that the first call to the fire department had come very late. "Secondly, the hospital personnel worked very badly, they did not take steps to evacuate people in the early stages of the fire," he said.