Any person who shall willfully set on fire or ignite or cause to be set on fire or ignited any building equipment or anything whatsoever at or within any mine when any person is present in such mine at the time, shall be deemed guilty of a felony, and upon conviction thereof, shall be imprisoned for not less than five years nor more than twenty- five years, provided, however, that if the life of any person be lost through the ignition or causing to be ignited of any such building, equipment or other thing as in this section provided, the person setting or causing to be set such fire shall be deemed guilty of murder in the first degree, and shall be dealt with according to the law at the time in force prescribing the penalty for such offense.