Section 140.30. Burglary in the first degree

A  person  is guilty of burglary in the first degree when he knowingly
  enters or remains unlawfully in a dwelling with intent to commit a crime
  therein, and when, in effecting entry or while in  the  dwelling  or  in
  immediate flight therefrom, he or another participant in the crime:
    1. Is armed with explosives or a deadly weapon; or
    2.  Causes  physical  injury to any person who is not a participant in
  the crime; or
    3. Uses or threatens the immediate use of a dangerous instrument; or
    4. Displays what appears to be a  pistol,  revolver,  rifle,  shotgun,
  machine  gun or other firearm; except that in any prosecution under this
  subdivision, it is an affirmative defense that  such  pistol,  revolver,
  rifle,  shotgun,  machine  gun  or other firearm was not a loaded weapon
  from which a shot, readily capable of producing death or  other  serious
  physical   injury,  could  be  discharged.  Nothing  contained  in  this
  subdivision shall constitute a defense to a prosecution for, or preclude
  a conviction of, burglary in the second degree, burglary  in  the  third
  degree or any other crime.
    Burglary in the first degree is a class B felony.