A train conductor is being treated in hospital after he and another man were allegedly stabbed on board an afternoon service.
The alleged incident happened on the 2.54pm Largs to Glasgow Central service as the train approached West Kilbride station at about 3.05pm on Sunday.
British Transport Police (BTP) said that two men aged 21 and 35 and a 26-year-old woman have been arrested in connection with the incident.
The 43-year-old ticket examiner was taken to Crosshouse Hospital in Kilmarnock, where his condition is described as stable.
Paramedics treated the other man at the scene for a minor injury to his body, but he did not need to go to hospital.
The train was held at West Kilbride while emergency services dealt with the incident.
A ScotRail spokeswoman said: “We do not tolerate crime on the railway and we are fully co-operating with British Transport Police in their investigation.”
The three people who were arrested are expected to appear at Kilmarnock Sheriff Court.
A BTP spokesman said: “Two men, aged 21 and 35, and a 26 year-old woman, have been arrested and are presently detained in police custody following an incident on board the 14.54 Largs to Glasgow Central service shortly after 3.05pm on Sunday, 31 May 2015.
“Two men, aged 43 and 40 years, were allegedly assaulted as the train approached West Kilbride station.
“The 43-year-old man was taken from the station to Crosshouse Hospital. He is presently detained with an injury to his body and his condition is described by hospital staff as being stable.
“The other man (aged 40) was treated at the scene by paramedics for a minor injury to his body. He did not attend hospital.”