The fight

Today I saw a street fight and I didn't know what to do except shouting "someone, please call the police!".
It happened really quickly. As I was getting out of the local supermarket, I noticed a commotion on the opposite sidewalk. It took me half a second to realize that it was a mob of about 10 guys beating one guy. All of the ten guys were Hispanic. The guy being beaten relentlessly was black. I don't even know how he survived. They were running after him and cornered him in front of the "chureria". He must have put his hands to protect his head and ducked. I was seeing their hands and their feet pounding his shrinked body. Everybody was watching, in awe and in silence on the sidewalk.
I shouted but not to the mob. I was way too afraid for that. I shouted to the other spectators. Surely someone had a cell phone. There was a couple in front of me. A black guy and his girlfriend, also black. They were locking their bikes when it happened and here they were, stunned with the bike locks in their hands.
Then it was over. As quickly as it had started. I saw one of the guy who had been part of the beating party, cross the street toward us. Outside the group he looked so normal, so unremarkable. He quickly disappeared in the crowd. I would have been incapable to recognize him.
I was still shocked when I heard the biker saying to his girlfriend "I think it was a brother."
She wasn't sure. I jumped in the discussion thinking I'll help. "Yes, it was" I say. The guy turns toward me incredulous. He decides to ignore my remark.
The cops are everywhere now.