Some of them have been critically injured in the accident and are now admitted to the North Bengal Medical College and Hospital in Siliguri.
Police sources said that some 50-odd students and their teachers from a Mumbai college had come to Darjeeling Hills for the excursion.
On Thursday night they were coming down to Siliguri from the Hills in three buses.
At Gayabari in Mirik in the Hills, driver of the last bus lost control and ended up dashing onto the second bus.
This made both the buses skid off the hilly road and fall into a gorge some 150 feet below the highway.
It was the local residents who got wind of the accident and informed Mirik police station. Police launched a rescue operation that continued well past midnight and managed to retrieve all members of the team.
The ones with minor injuries were taken to Mirik Hospital; those with critical injuries were rushed to North Bengal Medical College and Hospital. There has been no loss of life in the accident as yet.