The trio availed the cab service last night. As the vehicle moved a few hundred meters ahead, the man sitting in the front seat pulled out a country-made pistol and threatened the cab driver to stop the car, Anil Kumar Shahi, SHO, Sector 20 said.
The accused then threw cab driver, Tribhuvan, out of the vehicle and sped away, he said.
An FIR has been registered in the case on the complaint of the cab driver, police said.
Efforts are on to trace the trio and the vehicle, they added.