Police spokesman Ajith Rohana said the incident had occurred around 7.30 am at a roadblock manned by STF officers at Peduru Thuduwa.
The roadblock has been set up near a natural sand deposit at Peduruthuduwa in order to prevent illegal sand mining.
Rohana said a cab had moved toward the road this morning and had not stopped at the roadblock despite the orders of the STF officers to do so. The cab moved fast even after hitting two nail boards which had damaged the tyres.
The driver of the cab had even tried to run over the STF officers on duty and the officers had been compelled to fire at the vehicle which has not stopped, Rohana said.
Hours later, two persons wounded with gunshots were admitted to the Peduruthuduwa Hospital. Police say they were on board the cab which did not stop at the roadblock.
Police are recording statements from STF officers.
Police are also conducting investigations to arrest other culprits and the vehicle.