Police were busy in downtown Boston Wednesday night, after as many as 20 suspects attacked at least six people at Boston Common and the surrounding neighborhood, the Boston Globe reports.

Four elected not to press charges, according to authorities.

The attacks ranged from assault to unarmed robbery. Witnesses reported harrowing displays of group violence:

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McNamara said he was walking on Arch Street around 8:30 p.m. Wednesday when he saw about 10 people attacking a man who looked like an office worker from one of the downtown buildings.

"They were really coming down on this one guy," said [witness Joseph] McNamara. One person, a teenager with short cropped hair and red sweat shirt, was the most aggressive attacker, he said. "I didn't really realize what was going on until I was in the middle of it."

When the victim got up and tried to break away from his attackers, McNamara said, the assailants followed him as he crossed back and forth across Arch Street in search of a safe place to stop. The flow of attackers was "like a swarm," said McNamara. "It actually enveloped me at one point.

You can read the full report here.