The dead bodies were taken off at Jhansi railway station and sent for post mortem.
All the passengers were travelling from Agra to Coimbatore and were seated in S-8 and S-9 coaches.
Divisional Railway Manager Neeraj Ambisht said that the bodies would be sent to Coimbatore on Tuesday after post mortem.
The deceased were a part of a 68-member group that was returning after visiting Varanasi and Agra. "Shortly after we left Agra, the heat became unbearable and some people started complaining of breathing problems and uneasiness. Before we could get some help, they collapsed," said a member of the group.
The deceased have been identified as Bundur Palanisame, 80, Bal Krishna Ramaswami, 69, Chinnare, 71, and Dhiva Nai, 71.
Subbaraiyya, 71, has been hospitalised in Jhansi.