A man wielding a knife chased a man and a woman after watching them engage in sexual relations at a Towson parking garage early Sunday, Baltimore County police said.

The victims were on the roof at a parking garage near Pennsylvania Avenue and York Road at 1:30 a.m. Feb. 24 when they saw the man, who was touching himself inappropriately, according to a crime alert issued to the Towson University community. The man then chased the pair downstairs while brandishing a butterfly knife and yelling at them, according to police.

The alert describes the man as an individual between 5 feet 4 inches and 5 feet 10 inches tall with a medium complexion and short hair.