Smithson was among a group of people who had gathered on Swalm Street for a party on July 7, police said, when three men fired multiple gunshots at them, and then left the area.
It was not clear Thursday night exactly what role Smith played in the shooting.
In addition to Smithson, who was shot in the neck and chest, Nassau police said, a 21-year-old man was wounded in the left arm, a 17-year-old female was shot in the right thigh, and a 17-year-old male was shot in the left leg.
There was no information released by police Thursday, concerning the condition of the others who were wounded, or whether additional arrests are anticipated.
Smith was to be arraigned Friday in First District Court, Hempstead.