Former three-time world boxing champion Hector "Macho" Camacho was in a deep coma with a "very poor" prognosis Wednesday after being shot in the neck in Puerto Rico, his doctor said.
His heart stopped briefly overnight and he is being kept alive with a respirator and other machines, while doctors evaluate whether to declare him brain dead, they said.
"He is in a deep coma," said Ernesto Torres, the director of the Centro Medico hospital in Rio Piedras, Puerto Rico where Camacho was taken after Tuesday's shooting.
"The bullet damaged three arteries that run through the neck and as a result blood is not flowing well to his brain," he said.
Torres said the boxer was not responding to either pain or medicine.
"Macho's situation is very delicate. The prognosis is very poor," he said.
His mother, Maria Matias, arrived from New York early on Wednesday.
The Spanish-language TV channel Univision said his brother and children were also expected, as the family decides whether to disconnect an artificial respirator.
"His mother already knows that the outlook is not good, and we told her to prepare for the worst scenario.
We will continue to do tests tonight and tomorrow morning," Torres said.
"But we have to stress that Macho Camacho is breathing with a respirator and his blood pressure and pulse are being maintained by machines."
Camacho, 50, was being driven in a car when he was hit by gunshot from another vehicle outside a liquor store around 7pm local time, San Juan police said.
The driver, Alberto Mojica Moreno, 49, was killed in the shooting.
It was unclear if they were targeted or simply caught in a random act of violence.
Police said two assailants fled in an SUV but no arrests have been made and no motive has been disclosed.
They revealed Moreno was in possession of nine small bags of cocaine. A 10th bag was open inside the car.
Torres said Camacho's heart stopped at 4.15 am.
"We were able to pull him back with drugs. We gave him drugs and his heart started beating again," he said, adding that neurologists said they "cannot do anything for him."
"This is a process and we have to wait for two different indicators to declare brain death," he added.
Camacho was one of the most colourful boxers of the 1980s.
He has a career record of 79-6-3 with 38 knockouts, and over his career he took on all comers, including big names like Roberto Duran, Oscar De La Hoya, Julio Cesar Chavez, Sugar Ray Leonard, Felix Trinidad, Ray Mancini, and Greg Haugen.
Earlier this year, US police charged Camacho with child abuse for allegedly slamming his son into a floor at his ex-wife's home in Florida.
Camacho was accused of hitting and stomping on his son, police documents say.