IGP Pujith Jayasundara has assigned the Colombo Crime Division (CCD) and 11 Police teams to investigate into the shootout that occurred at the Kudawella fisheries harbour in Tangalle.
The IGP has also instructed all Police teams to carry out the investigations expeditiously and bring all culprits to book.
Two gunmen, who came in a motorbike, had opened fire at a group at the fisheries harbour, the Police said after initial inquiries.
The incident left four dead and several others injured.
The Police Media Unit said a dispute between two groups of fishermen might have led to the shootout.