Indian police have launched a major manhunt to nab five inmates of a juvenile home in the eastern state of Bihar who escaped after killing the warden.

The incident took place in Purnea town, some 325 km from state capital Patna.

"The teenagers shot the warden dead Wednesday after he moved the juvenile justice board and got an order to shift them to another remand home," a police official said Thursday.

This was after the warden discovered that the five teenagers were addicted to cough syrup, he said, adding that the accused also shot another inmate dead before fleeing the home.

"A probe has also been ordered to ascertain how the five got hold of a gun. A manhunt has been launched to track all of them down," the official said.