Columbus police spokesman Sgt. Rich Weiner says the suspect confronted one victim inside the building near Miami-Jacobs Career College. He said other people inside intervened and took away one knife the suspect was using.
Weiner says those who intervened didn't realize suspect had a second knife.
Three male victims are in critical condition, while a fourth man has minor injuries. The suspect is in critical condition. His name hasn't been released.
A school spokesman says he doesn't know whether the victims were students or staff.