Mo. Rev. Stat. § 565.050: Assault, first degree, penalty.

1. A person commits the offense of assault in the first degree if he or she attempts to kill or knowingly causes or attempts to cause great bodily harm to another person.

2. The offense of assault in the first degree is a class B felony unless in the course thereof the person inflicts great bodily harm on the victim, or if the victim of such assault is a special victim, as the term "special victim" is defined under section 565.002, in which case it is a class A felony.