Officers and medics responded to the scene, near 7th Avenue and South Main Street, at about 12:50 p.m. after receiving a report of a stabbing.
Arriving there, they found a 62-year-old man with bleeding stab wounds to the shoulder and abdomen. He refused to provide any information about the attack and was taken to Harborview Medical Center for treatment of serious but non-life-threatening injuries.
Witnesses said the victim was attacked by another man armed with a machete that had a silver blade and a decorative red handle.
The attacker then fled the scene on foot, reportedly heading east toward Interstate 5 from Kobe Terrace Park.
The suspect is described as a black male, 6 feet to 6-feet-2-inches tall, with short hair, clean shaven, wearing a long sleeve beige shirt and dark pants.
Officers searched the area for the suspect using a K-9 dog, but were unable to find him.
Anyone with more information is asked to call 911.