The driver and conductor of a train helped a traveller who collapsed at Felixstowe station.
Trains are delayed by up to 20 minutes between Ipswich and Felixstowe as a result of the incident.
Staff on the 5.28pm Felixstowe to Ipswich service waited with the man for an ambulance to arrive before starting the journey.
Disruption is expected until 10pm.
The East of England Ambulance Service sent a rapid response vehicle and treated a man in his 20s.
He was taken to West Suffolk Hospital for further care.
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