Amos Sykes, 35, of Quincy, was ordered held without bail following a dangerousness hearing at Boston Municipal Court Wednesday.

“This brutal, random attack is exactly the type of incident for which it’s in the best public interest to move forward with a dangerousness hearing,” Suffolk DA Kevin Hayden said following the hearing.

Sykes was arraigned Monday and charged with assault and battery causing serious bodily injury, indecent assault and battery, assault to rape, strangulation, assault and battery with a dangerous weapon and assault and battery.

Police responded to the area of West Canton Street and Appleton Street at around 9:40 p.m. Saturday after several witnesses in the area heard a woman screaming and saw a suspect punching her in the head as he sat on her, according to a BPD statement.

When police arrived, some of those witnesses were purportedly fighting with Sykes in the woman’s defense, but Sykes fled before police caught up to him. The alleged victim told police she was walking down Columbus Avenue when Sykes grabbed her, forced her to the ground, punched her and tried to rip up her clothing.

“This was a nightmarish attack that left the victim bloodied and bruised, and would likely have resulted in an even worse outcome if not for the extraordinarily brave intervention of a Good Samaritan,” Hayden said.