NEWARK, N.J. (CBSNewYork) — A year-long drug investigation led police to a popular city recreation center in Newark, and some employees were recently arrested.

Federal investigators said while locals were enjoying the Rotunda Recreation Center, some who work there were running a drug ring out of the facility.

Mayor Ras Baraka was enraged.

“I was completely perturbed. Angry. Upset. I finished yelling at a whole bunch of people this morning. I’ve got some more of that to do,” Baraka said.

The U.S. Attorney’s office has charged 12 people, including members of a gang connected to the Bloods street gang, with selling heroin, fentanyl and crack cocaine.

Rotunda Recreation and Wellness Center (Photo: CBS2)

“These gang members used the Rotunda Recreation and Wellness Center to conduct narcotics transactions and as a stash location for the narcotics. The rec center is supposed to be there for the community, not for drug dealers,” U.S. Attorney Craig Carpenito said.

Three seasonal employees were among those arrested. At least one of them had a prior drug record and still hired by the city, partly because current city policy doesn’t require part-time employees to undergo a background check — even if the work involves being around children.

The mayor said that policy will change.

“In the future we will do record checks, as we move forward, on all employees, even those who are not normally bound by record checks,” Baraka said.

“It sickens you to see that people that were given a job on a seasonal basis that maybe made a mistake in the past and were given a pass to come to a job and engaged in criminal activity,” Newark Public Safety Director Anthony Ambrose said.

Baraka said the three part-time employees were immediately suspended and will be fired.