It happened around 2:15 Sunday morning.
Dylee Gonzalez captured video from inside a bar on 2nd Street near Chestnut Street.
It shows at least one woman in the group being punched and kicked relentlessly.
"At one point I know she was being completely stomped out," said Gonzalez.
Police officers who were stationed nearby heard a gunshot fired and ran up the block. They arrived to find mayhem and people screaming.
Someone labeled the shooter in the crowd and police grabbed him. Officers say a black handgun fell from his waistband.
"As soon as he pulled out the gun, I ran away immediately," said Gonzalez.
Police say they tried to taser the suspect, later identified as 28-year-old Christopher McRae of Camden, but it had no effect on him.
McRae ran off but was later arrested nearby.
"It was intense. If the cops didn't show up when they did, somebody could've died," said Gonzalez.
Gonzalez hopes by sharing the video he caught, it will draw attention to the violence and help police with their investigation.
Authorities have not said what sparked the brawl. Police continue to investigate.
McRae was charged with Violation Uniform Firearm Act, Recklessly Endangering Another Person, Resisting Arrest and related offenses.