Kochi, Feb 15 (PTI) Armed guards of a merchant vessel allegedly opened fire at a fishing boat off Alapuzha waters this evening, prompting the Coast Guard to launch a search operation to trace the vessel. Coast Guard sources said a Coastguard aircraft and a ship are trying to track down the vessel from which the shots are alleged to have been fired. The armed guards in the merchant vessel are alleged to have fired at the fishermen in a traditional boat suspecting them to be pirates. Two fishermen were reported to be injured in the firing. The incident occurred around 4.30 PM this evening, sources said. The fishermen, said to be from Kanyakumari in Tamil Nadu, had put out to sea from Needakara coast in Kollam district this morning. Coastal police and fishing department are also engaged in search operations.