Police say the attack is no game. "Paint balls are high velocity projectiles that can cause serious injury," Lt. Zach Perron told KTVU.
He said the first attack happened at 8:31 p.m. Tuesday near the intersection of Newell Road and Dana Avenue.
The second occurred just three minutes later a few blocks away in the 700 block of Melville Avenue.
In both cases, the victims told police they were ambushed by what appeared to be a passenger in an older model, gold colored car.
"Somebody drove up behind them in a vehicle and fired 12 to 14 green paintballs," said Perron.
Five people were targeted, with three of them getting struck including a man in his 70's. No one was seriously hurt.
Perron said the attacks could face charges ranging from misdemeanor battery and vandalism up to felony assault if someone does get seriously injured.
The manager of Santa Clara Paintball at the fairgrounds in San Jose tells KTVU paintballs are meant to be fun, if fired in a controlled environment and the users wear protective clothing.
Andrew Macias says it's disheartening to see people abusing a toy that has the potential to cause injury.
"Our guns are turned down but they're still shooting at 220 feet per second," he told KTVU.
"That's 180 miles an hour and you can shoot somebody with a marshmallow in the eye at 180 miles an hour it will do serious damage."
To add insult to injury, the attackers treated the violence as a joke.
"The second group of people reported hearing, as the car drove away, a male voice from inside the car kind of laughing and carrying on," said Lt. Perron.
Bill and Monique Heinz live in one of the neighborhoods where the attacks occurred.
"Everyone looks out for one another and this is a very unusual occurrence," said Bill.
His wife Monique says they'll now keep a lookout for an older, gold sedan, and spread the word to their neighbors. "They do a lot of neighborhood emailing where they email everybody if something's up."
Meanwhile, Andrew Macias says he hopes the attacks don't tarnish the image of a popular sport for kids and adults, who just want to have a good time without getting hurt.
"I don't know what these hooligans are up to but it's not fun getting shot if you're not expecting it," he said.