KIRO reported the suspect was identified as Christopher R. Morisette, 29, who had an extensive criminal history and spent time at the state's largest psychiatric hospital.
The news outlet said his criminal history includes “numerous violent convictions,” such as that he allegedly pulled a box cutters on police officers.
The Seattle Police Department said the incident was first reported around 10 a.m. on 6th Avenue and Olive Way, located near the headquarters of Nordstrom.
Police tweeted two people were transported to Harborview Medical Center. One of the victims was a 75-year-old man who was listed in stable condition.
Further details about the second victim were not immediately available. A third person was treated at the scene and declined transport, police said.
The incident drew a large emergency response in the downtown area, according to video from a KOMO News reporter.
The suspect was taken into custody according to Seattle Police, who added the man's clothing and knife were recovered in the area.
The incident closed 6th Avenue between Pine Street and Olive Way, Q13 Fox reported.