Two men in their 20s boarded the bus at around 6.30pm and they appeared to enter into a dispute about payment with the bus driver.
One of the men became aggressive and pulled out a knife. He stabbed the bus driver in the stomach and both of the men then rushed off the bus.
The driver was taken to Örebro University Hospital, where on Tuesday he was still being treated for severe injuries.
The men, who are now wanted on suspicion of attempted manslaughter, are still at large, despite the fact that several police units have joined the hunt for them.