Chris Brown -- Extra Cops at Concert ... He Attracts Certain 'Type of Crowd'

Chris Brown had scores of cops and security at his concert in Concord, CA Saturday because of the "type of crowd" he attracts.

Concord PD tells us there were 40 cops patrolling the Concord Pavilion to ensure calm, along with 20 security guards from the venue. An official from Concord PD says his department did its research and learned there was "a pattern" to Brown's concerts ... fighting and even a shooting.

The official told us, "Chris Brown brings in a type of crowd."

We're told there was "chest pumping" inside the concert but nothing developed into a full-blown fight. Around 10 people were taken by ambulance to a local hospital for alcohol poisoning.