Workers at New York City’s two juvenile detention centers are struggling to control an exploding population of minors charged with serious crimes, an influx that has led to assaults, threats and the discovery of weapons including ceramic blades, razors and scalpels, the Department of Investigation said Thursday.

City investigators began examining the centers after 2017, when state legislators signed the Raise the Age law, which sent most 16- and 17-year-olds accused of crimes directly to Family Court or to judges with special training. The law, signed after crime had plunged, meant that even those under 18 accused of violent crimes were no longer placed in adult jails on Rikers Island and were sent instead to the juvenile centers: Horizon, in the Bronx, and Crossroads in Brooklyn.

Between April 2018, six months before the law was enacted, and May 2023, the number of residents of the centers who were 16 and older and accused of murder rose to 134 from seven, according to a 75-page report from the department.

Staff members were not equipped to deal with the deluge, according to the report. The vast majority of workers said that residents run the facilities, according to the report. It described riots where the police were called after staffers were punched and kicked.

Employees were so worried about being stabbed that they wore layers of clothing under their uniforms, and supervisors have told employees to let minors keep contraband like marijuana, because it kept them calm.

New workers were told to give “residents what they want if you don’t want issues,” the report said.

After one worker was slashed, others overheard the minor who did it say that “cutting season on staff has just begun, and we are 17 so nothing will happen,” the report said.