NEW YORK (CBSNewYork/AP) — Thirteen people have been arrested in a drug sweep and charged with allegedly selling narcotics at public housing facilities in Brooklyn, prosecutors said.

Brooklyn District Attorney Kenneth Thompson said Thursday the arrests follow a nine-month investigation into drug sales near schools.

Officers made 27 undercover purchases since October 2014. Most of them occurred near two elementary schools.

“Members of the community reached out to law-enforcement with complaints about narcotics and related violence, leading to this successful investigation,” Thompson said in a news release. “We will not allow hard-working people to be held hostage by violent gangs and drug dealers who operate in their midst and these arrests will bring a measure of safety to residents in these housing developments.”

The suspects were arrested Wednesday after police executed search warrants at the Bushwick and Borinquen Plaza housing developments in East Williamsburg.

During one raid, officers found 68 glassine envelopes of heroin and 10 grams of crack cocaine. Forty-nine grams of heroin were recovered during a separate search.

The 13 suspects face drug sale and drug possession charges. They are scheduled to be arraigned Thursday.

They face sentences of one to nine years behind bars if convicted.

Prosecutors said more arrests are expected as part of the ongoing investigation.

Since July 2014, the Brooklyn DA’s office and police have teamed up for seven takedowns of alleged drug traffickers in public housing developments, leading to charges against more than 50 people, authorities said.

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