Passengers on a rush hour Muni ride got more than they bargained for Monday, when a fight between two riders ended in a bloody mess.

Police say that the incident happened on a Muni bus at the intersection of Powell and Market Streets, at 8:14 a.m. Monday.

According to the San Francisco Police Department, a 56-year-old man was walking toward the rear of bus when a 21-year-old man gave him a shove.

In response, the older man pushed the younger, then punched him in the face, police say.

The younger man then allegedly escalated the situation, as he "pulled a knife out and began stabbing" the older man, police say.

The victim fell to the ground, then pulled himself up and "ran for aid," according to the SFPD.

The stabbing suspect was arrested at the scene, police say. The victim was transported to an area hospital for treatment of his injuries, which police say are not life-threatening.

Related: Gang Of Women Beats And Robs Fellow Muni Patron