Another woman, who is in her 20s, has been seriously injured.
This incident happened earlier this afternoon at Knocks Park, near Ballisodare.
The train involved was the 3.05 service from Sligo to Dublin Connolly.
Its understood the women tried to jump out of the way of the train but didn’t get clear in time.
The older woman’s body remains at the scene.
The younger woman has been rushed to Sligo University Hospital in a serious condition.
Irish Rail says 100 people remain on the train, and cannot be moved until investigators give the go ahead.
They could be there for some time.
Bus transfers are in operation for passengers of other services, connecting Boyle to Sligo.
