The police Special Task Force (STF) fired tear-gas inside the Welikada prison after a tense situation arose involving prisoners and prison guards.
The situation arose when the STF attempted to search the prison premises to look for illegal items in the possession of the prisoners.
According to the police, some prisoners had objected to the search operation resulting in the tense situation.
The prisoners then took the weapons from the prison armory and fired at the STF and army reinforcements.
Several people were injured in the shooting.