The blast happened before dawn yesterday at a depth of 300 metres located in the eastern city of Kirovsk, the State Emergency Service said in a statement.
Officials said they were continuing their search for the two missing men.
Accidents are a regular feature at Ukrainian mines, most of which are located in the country's industrial eastern region, where pro-Russian rebels now control over a dozen towns and cities.
Many of them are underfunded and poorly equipped, and safety violations are rife.
