Several Rikers Island inmates were arraigned on new charges Monday after a guard was brutally attacked Saturday evening, according to officials.

Four 18-years-olds could each spend the next 25 years in prison if convicted of gang assault and related crimes in the vicious attack on a correction officer at a jail facility Saturday evening.

Prosecutors said that Steven Espinal, who had been jailed on an attempted murder charge, planned the attack, throwing a first lunging punch at Correction Officer Jean Souffrant. Souffrant's head hit a concrete wall, and investigators said the three other inmates joined in as he hit the floor. Prosecutors said Espinal was upset because Souffrant had written him up for violating jail rules.

Souffrant suffered a brain bleed and a broken spine near his neck. He is hospitalized in serious condition, but he is conscious.

The correction officers' union blames the inmates but also Mayor Bill de Blasio, saying the administration no longer allows violent young inmates to be placed in solitary confinement.

The mayor's office said de Blasio has proposed spending $200 million over the next decade to improve officer safety, but a spokesperson for the mayor added that the correction department will not change jail rules following Saturday's attack.

"We have no intention of moving backward on our solitary reforms. It's clear that more solitary and isolation doesn't translate to less violence, and can hurt people instead of helping them," the mayor's office said in a statement.

The union said the four charged now go back to Rikers Island with no immediate penalties, their TV and common area privileges intact. Correction officers worry they no longer have the ability to prevent these young prisoners from meeting again to plan another attack.