Animesh Ghosh of Aizawl died at the Lunglei district hospital last night.
Three others - Ravi Chanda of Baghbasa, Tripura, Uma Kant Bhandari of Dumka district in Jharkhand, and Sushanto Rai of Assam's Cachar district - died on the spot when a vehicle carrying them rolled down into a deep gorge near Sekhum in Lunglei district.
Though the cause of the accident was yet to be determined, the driver dozing off while driving was not ruled out, the SDPO said, adding that the driver was still missing.