The assault happened Sunday night when Michael Fejes, 65, was out for his nightly walk near Hickory Park.
A car pulled up with two or three young men inside, according to Fejes' son.
They shouted out to him and as he turned to look he was shot several times with a paintball gun. The young men laughed and drove off.
Two of the paintball pellets struck Fejes in the eye, causing what his son called "severe damage." He was unable to see out of his right eye.
"He said it was the most intense pain he ever felt," the victim's son, Michael Fejes Jr. said. "Immediately the impact just radiated throughout his head."
Police say they found and arrested three suspects Tuesday around 3:45 p.m. in the area of Cabrillo Boulevard and 233rd Street. They recovered several paintballs and a paintball gun.
The suspects were identified as Tyler Walters, 20, of Torrance, Lynn Johnson, 20, of Hawthorne, and Gabriella Semana, 18, of Lomita.
Fejes had been scheduled to undergo surgery at UCLA, but the procedure had to be canceled because of an infection forming in the wound, his son said. He will be evaluated again in two weeks to see if the infection heals.
"This attack was on a 65-year old man that was going for a walk and he may now lose his vision and have other long-term consequences as a result of this 'prank,'" Michael Fejes Jr. wrote. "The laughs that may come out of this are not worth the damage that it causes."
Fejes Jr. said after he posted on Facebook about the attack, a number of people reached out to him about other paintball attacks in the area that damaged cars and houses.
Torrance police warned that paintball guns can be dangerous, especially if shot at a person's eye or other sensitive area.
"This could very well be a practical joke, but it's actually very serious," said Torrance Police Sgt. Ronald Harris. "Shooting at innocent people is not the right thing to do."
Police say two other people were also shot with paintballs around the same time as the attack on Fejes, with minor injuries.