Miners' relatives gathered outside the Zasyadko mine in separatist controlled Donetsk after the blast went off early on Wednesday. More than 200 workers were reportedly underground at the time of the explosion, DW reports.
"A terrible tragedy took place this morning at Zasyadko. There are victims, currently numbering 32," Volodymyr Groysman, the president of Ukraine's parliament told lawmakers in Kyiv, calling for a minute of silence.
A rescue operation is under way at the site to free trapped miners. The head of the local mining safety service, Vladimir Tsymbalenko, said poisonous gas was being removed from the shaft to clear the way for emergency workers, DW news agency informs with reference to Reuters.
Donetsk News Agency cited rescue services official Yuliana Bedilo as saying the explosion was caused by a mixture of gas and air – a common cause of industrial mining accidents. A 2007 explosion at the same mine killed 106 people.
The shaft was in an area of eastern Ukraine controlled by pro-Russian separatists, who have been fighting forces loyal to the government in Kyiv for almost a year. More than 6,000 people have been killed in the conflict.