With another body discovered in Brentwood, N.Y., this week, the Suffolk County Police Department has announced its response: the arrest of what it said were 35 members of MS-13, a gang with roots in El Salvador and Los Angeles that has long been terrorizing the Long Island town.

“It’s a significant percentage,” Timothy Sini, the Suffolk police commissioner, said in an interview on Friday. “This is not 1 percent — this is a major shot against the criminal enterprise.”

Mr. Sini said it was only the beginning. Five of the 35 people arrested, he said, are “violent, high-ranking gang members” who are in federal custody, having been charged under the RICO organized crime act.

On Monday, the police found skeletal human remains in the woods near the Pilgrim Psychiatric Center, which they identified on Thursday as belonging to Jose Pena-Hernandez, 18. His body was the sixth found in Brentwood in a little over a month.