An Escondido police officer said the off-duty deputy shot in Downtown San Diego knew he would get hurt but still jumped in to help his younger brother.
NBC 7 is not identifying the police officer because he often works undercover.
Jason Philpot, an 11-year veteran of the San Diego County Sheriff's Department was shot near Island and Sixth Avenue early Monday morning after he was leaving the Metallica concert with his brother and friends.
He was released from the hospital Tuesday.
"I just remember saying goodbye to Jason and myself and my partner were walking 15 to 20 yards in front of Jason and his brother when we heard the shots," the Escondido police officer told NBC 7.
The officer said neither he nor the other officers had their gun with them because off-duty law enforcement officers cannot take their weapons into Petco Park.
Still, the officer said he instinctively reached for his gun--which wasn't there-- when Philpot's brother, Josh shouted one of the suspects had a gun.
"What I noticed was my friend Jason was running," he said. "He was on the ground."
The 35-year-old deputy was shot three times--once in the upper torso, twice in the arm.
The officer said he and his partner ran to give Philpot medical aid. Even after being shot three times, Philpot was calm and joking.
Philpot was taken first to Sharp Coronado Hospital and later transferred to UC San Diego Medical Center, police said.
"If it would have hit something, it could have gone left or right, up or down a few inches--we could be talking about a different story right now," the officer told NBC 7.
Josh told NBC 7, his brother jumped in front of the gun to protect him and had been trying to wrestle it away when he was shot by the suspect.
"If I could relate one thing about Jason--one--he is a true warrior, [a] true hero. Jason literally went to the gun. He literally stopped his brother from being killed in my opinion," the officer said.
He added Philpot will come back and "be tougher than ever."
A second person who was walking in the street was shot in the arm, according to San Diego police. Their injuries are not considered to be life threatening.
The suspect who fired the shots was described as a man in his 30's, about 5 feet, 10 inches tall, weighing about 160 to 170 pounds with shoulder length dreadlocks. He was last seen running towards K Street.