Authorities said the man was stabbed under the armpit while standing on the platform at the 7th and Figueroa Metro station at 2:06 p.m.
The suspect fled the scene after the stabbing. He was described as a black male, 20 to 25 years old, between 5-foot-6 and 5-foot-8 inches tall, about 160 pounds, with a mustache. He was last seen wearing a skull cap, a long sleeve white shirt and blue jeans. He was also seen carrying a plaid shirt.
The victim was taken to County-USC Medical Center with non-life threatening injuries.
