The three, in their early 20s and students of a private college, had come from Kochi to attend the marriage of their friend's sister today at Aroor when the tragedy struck them.
After having dinner at the friend's house which is adjacent to the railway track in Aroor, the trio had gone out for a stroll and did not return.
The deaths came to light this morning when their bodies were found strewn near the track, police said.
In another incident, three youths, who had put out for fishing in backwaters from Kadachira in Kollam district early this morning, drowned when their country craft capsized in heavy rains, police said.