A Rikers guard was hospitalized on Friday night after being punched in the face several times by an inmate, according to the Department of Correction.

According to a spokeswoman for the department, the officer, whose name has not been released, was on shift at the Otis Bantum Correctional Center when he was punched on Friday. A Captain who "assisted" the officer was also hospitalized, with a hand injury. The inmate, who has not been named either, was also hospitalized and has been rearrested to face additional charges. The department declined to comment on the injuries he sustained.

Sources told CBS2 that the inmate was allegedly a member of the Crips gang, and that the attack was "unprovoked," although the DOC again declined comment.

"This assault on our officer was unacceptable. Such attacks against the hardworking men and women who serve in our department will not be tolerated," DOC Commissioner Joseph Ponte said in a statement. "We have zero tolerance for assaults on staff and are deeply committed to creating a culture of safety at the Department of Correction. This inmate has been arrested."

The alleged assault took place on the same day that 592 new correction officers—377 men and 215 women—were sworn in.

Addressing the new officers, Mayor de Blasio spoke at length about Rikers' negative reputation. "We have to be real about the past," he said. "Because the past was not what it should have been. We know, for too many years, Riker's was a dehumanizing place for the people who worked there and for the inmates alike."

The NY Times reports that this new class of officers has been more carefully screened than in the past—applicants who had been rejected from the police department were barred, as well as applicants with criminal records or gang affiliations. Just shy of 60 of the new officers are military veterans, more than 100 have Civil Service jobs on their resumes, and one has a Ph.D. in business economics.

The tightened selection process is in keeping with the mayor's Rikers Island reform agenda. In June, the city settled Nunez v. City of New York, a 2012 class action lawsuit claiming that 11 inmates had suffered "unprovoked" beatings at the hands of Rikers guards. As part of the settlement, de Blasio instated a new federal monitor to oversee Rikers reforms, like a new, explicit policy for documenting and reporting use of force against inmates; a trial run of body cameras for correction officers; and serious penalties, including job termination, for offending officers.

The City has also committed $200 million to train guards on violence reduction and interacting with mentally ill and adolescent inmates, as well as more complete security camera coverage, and riot gear.

"You couldn't be here a moment too soon," de Blasio said to the new guards on Friday. "We have to rewrite the story of Rikers Island. We simply have to. And you will be the authors of that new history."

Following Friday's assault, New York City Correction Officer's Benevolent Association president Norman Seabrook was more hesitant about reform.

"Rikers reform is necessary and something we support, but our members need to be part of the conversation around reform and we need to be consulted on policies that limit how we deal with dangerous inmates," he said in a statement to CBS.

A report released in October by the office of Comptroller Scott Stringer [PDF] emphasizes that violence in NYC jails continued to increase this year—as it has, steadily, since 2008—even as Department of Correction funding has gone up.

According to the report, the annual cost-per-inmate in NYC jails increased 17 percent in FY2015—the largest percentage rise in inmate spending in the last three decades—to $112,665.

At the same time, the rate of infractions for fights and assaults in NYC jails has increased 19 percent. DOC officer-on-inmate use-of-force incidents and allegations nearly doubled this year, from 370 to 471 complaints per 1,000 inmates. Inmate-on-staff assaults increased 46 percent, from 71 to 103 assaults per 1,000 inmates.

According to the City, inmate assaults on staff with "serious injury" have dropped 11 percent in 2015 to date.