NEW YORK (CBSNewYork) — Authorities rounded up 37 alleged members of two violent Harlem gangs that have been fighting over turf, on Thursday.

Manhattan District Attorney Cyrus Vance said four of the suspects have been charged with shooting at Tyrone Howard last October, who in turn is charged with killing NYPD Detective Randolph Holder.

“Who was charged in the Holder indictment with the murder of Officer Holder,” Vance said.

Those arrested were allegedly members of the East Army and 600 Gutter Gang.

“And so each week we have been taking down an average of three or four gangs,” Police Commissioner Bill Bratton said.

The numbers show 81 gang related shootings this year — that’s a lot, but far fewer than the 158 that took place in the same time frame last year.