The incident took place sometime between 3 am and 5 am at Tamseng village near Meghalaya-Aassam border.
The bus was on its way to Agartala from Guwahati when it fell into the 80-feet deep gorge.
"The rescue operations are over and investigation has begun to ascertain the cause of the accident," the officer said.
A Tripura official said in Agartala that 27 people died on the spot.
The driver of the bus, who also died, lost control of the bus when he was taking a turn in the terrain cramped Assam-Agartala highway.
Tripura Transport Minister Manik Dey said that a state government team had left for the site.
He said the place where the disaster site was "extremely accident prone". "Every year a number of accidents have occurred in the area. killing many people."
The depth of the gorge is over 80 feet.