Any person who unlawfully and maliciously causes by—
     (a) any explosive substance an explosion of a nature likely to endanger life or to cause serious injury to property shall, whether any injury to person or property has been actually caused or not, be punished with imprisonment for life, or with rigorous imprisonment of either description which shall not be less than (ten years, and shall also be liable to fine;
     (b) any special category explosive substance an explosion of a nature likely to endanger life or to cause serious injury to property shall, whether any injury to person or property has been actually caused or not, be punished with death, or rigorous imprisonment for life, and shall also be liable to fine.