A fire in a Moscow industrial estate killed 17 workers from the former Soviet republic of Kyrgyzstan, reports said Saturday.
The victims were all young women, according to comments made to the Interfax news agency by Abdygan Shakirov, described as a spokesman for the Kyrgyz community.
"They were in a changing room and could not leave. The smoke had blocked their way," he said.
Earlier reports quoted a spokesman for the emergency management authorities as saying that the workers were in a burning store room in a printing press in the north-east of the capital, Moscow.
"During the fire-extinguishing operation a room was discovered which had been sealed off by the fire," a spokesman for the authorities told Interfax.
Detectives launched an initial investigation into possible arson, but later said they could not rule out a short-circuit or negligent handling of the fire as the cause for the blaze.
"Unfortunately there is a high number of victims," Moscow Mayor Sergey Sobyanin wrote on Twitter.
Hundreds of thousands of migrant workers from Central Asia, the Caucasus, Ukraine and Belarus earn a living in Russia to help support families in their home countries. They often live in appalling conditions.
The Kyrgyz who lost their lives in Saturday's fire were in Moscow legally, a spokesman for the interior authorities said.
Co-workers gathered at the site of the fire.
Images during the blaze showed thick black clouds of smoke over the multi-storey building. The fire brigade deployed 140 firefighters to put out the flames.
Twelve people were rescued from the burning building, and four were taken to hospital, where one woman succumbed to her injuries.