The priests Sri Lankan (30), Michael (55), Sahayaraj (56), and Jesu (41) of a church near Kodaikanal, were returning from Sivakasi when the accident occurred.
All the four died on the spot.
In another incident, three occupants of a 108 ambulance were killed, after it collided head on with a bus in Tirupallani in Ramanathapuram district, about 180 kms from here, police said today.
The incident occurred when one Velumani (68) was being taken to the Ramanathapuram government hospital for treatment, along with his daughter Muthu Mari.