The deceased have been identified as Rohit, Rinku and Satbir (all between 18 and 23 years of age), they said.
Another seriously injured person, Rajan, has been hospitalised, the police said.
All of them belonged to Kail village in this district, thay added.
The deceased were heading towards Jagadhri for work when a Punjab roadways bus hit their motorcycle, the police said.
The bus driver fled from the spot, they said adding that case had been registered.