METRO police said there were three people on the bus at the time, which was traveling along the East Freeway at Lockwood. METRO spokesperson Jerome Gray says the three people, who knew each other, got into an argument. That's when one man reportedly pulled out a pocket knife, turned around and stabbed one of the other men.
Police say the stabbing victim was wounded on the left side and was taken to St. Joseph's Hospital. Investigators say he was breathing and conscious.
The alleged stabber fled the bus on foot, but he was caught a short time later.
Tony Hernandez, 32, has been charged with aggravated assault with a deadly weapon.
METRO police are still investigating the stabbing. They say it's still unclear what the argument was about.