Surgeons amputated the lower right leg of the off-duty police officer who was critically injured when a fellow cop shot him Saturday in a case of mistaken identity.

The decision by doctors at St. Barnabas Hospital, in the Bronx, to remove the leg of Officer Eric Hernandez, 24, “was necessitated by the continuing deterioration of the condition of the leg, compromising his medical condition even further,” the hospital said in a statement.

Officer Hernandez was shot early Saturday morning in “friendly fire” from another officer who did not know he was a cop. The shooting occurred after Officer Hernandez was assaulted by five men inside a Bronx White Castle restaurant. An on-duty policeman responding to the assault found Officer Hernandez holding an individual at gunpoint in the restaurant’s parking lot, police said, and the policeman reportedly shot Officer Hernandez when he refused to drop his weapon.

On Monday, three men were arrested in connection with the initial assault, which was captured on a security camera inside the restaurant. According to a law enforcement source, who spoke anonymously because the official charges had not been officially released yet, the three men were expected to be arraigned on charges of attempted assault in the first degree, attempted gang assault in the first degree, and assault in the second degree. Police said they are still looking for two other suspects.

Meanwhile, Officer Hernandez, who was shot three times – once in the abdomen and once in each leg – has remained in “very critical condition” for the past several days, according to a hospital spokesman. A hospital source said Officer Hernandez had received more than 200 units of blood in transfusions: The average adult’s body contains six to eight units of blood.

Police have reported the on-duty officer who shot Officer Hernandez did so within police guidelines.