Former three-weight world champion Hector 'Macho' Camacho is fighting for his life after being shot in the face during a gun attack.

The Puerto Rican, 50, was sitting in his car in the city of Bayamon on Tuesday night when the incident occurred, The Mirror reports.

He miraculously survived the gunshot wound, but a passenger who was with him inside the vehicle lost their life.

Camacho is currently in a critical but stable condition in hospital, though doctors believe that he could be left paralysed as a result of his injuries.

"Camacho's condition is extremely delicate," read a statement from a doctor who is treating the retired fighter. "His physical condition will help him but we will see.

"He went into cardiac arrest. The doctors were able to get his heart started again with the medicine and we are maintaining his blood pressure and pulse stable medically right now to see whether during this morning, afternoon or evening we see a positive change."

Camacho is one of Puerto Rico's most successful fighter, winning 79 of his 88 fights, including a knockout victory against Sugar Ray Leonard.