He was rushed to a helicopter and taken to a Vancouver area hospital to treat what Knapton described as “very serious” injuries.
“(His) prognosis right now is still unclear,” Knapton said.
Police were called to the scene to investigate a reported pepper spraying incident but quickly found the stabbing victim.
RCMP arrested a 23-year-old Vancouver man without incident on Monday.
The suspect was due in court Tuesday after press time to face charges in connection with the assault.
The festival was largely a peaceful gathering of music fans, according to Knapton.