(1) A person commits first degree burglary if the person knowingly enters unlawfully, or remains unlawfully after a lawful or unlawful entry, in a building or occupied structure with intent to commit therein a crime, other than trespass as defined in this article, against another person or property, and if in effectingentry or while in the building or occupied structure or in immediate flight therefrom, the person or another participant in the crime assaults or menaces any person, the person or another participant is armed with explosives, or the person or another participant uses a deadly weapon or possesses and threatens the use of a deadly weapon.
(2) First degree burglary is a class 3 felony.
(3) If under the circumstances stated in subsection (1) of this section the property involved is a controlled substance, as defined in section 18-18-102 (5), within a pharmacy or other place having lawful possession thereof, such person commits first degree burglary of controlled substances, which is a class 2 felony.