The police said that gunmen who arrived in a vehicle opened fire at the bus.
Underworld member Aruna Udayashantha, alias Samayan, was killed in the shooting incident.
The police said that two prison officers were also killed in the shooting incident.
The police said that five police teams have been deployed to investigate the shooting incident.
The police media unit said that according to initial investigations, the gunmen had been wearing clothes similar to a police uniform. (Colombo Gazette)