Police have made a sixth arrest in a robbery case that saw three teens held at knife-point for more than an hour near Polo Park.

On July 12, suspects held a group of teenagers at knife-point under a railway bridge east of Empress Street, near Polo Park. The group, consisting of one 18-year-old man and two 18-year-old women, were robbed and forced to hand over debit cards, cash and cellphones.

The male was also assaulted in the upper body. One of the suspects wore a "scary clown mask," police said previously.

Eventually, the victims were allowed to leave and police were notified.

Officers earlier announced the arrests of four suspects ranging in age from 17 to 19.

On July 28, a 21-year-old male suspect turned himself in.

In addition to the fifth suspect taken into custody, police have now arrested a sixth suspect after calling for the public's help in finding him.

Joseph Jordan Henderson, 18, turned himself in on July 29, said police. He faces charges for robbery and forcible confinement.