Costa Rica’s National Coast Guard seized over one ton of cocaine being transported on a small-scale fishing boat in the country’s Pacific, said police sources Monday.

The operation was carried out on Monday when the Coast Guard intercepted the boat and detained its four crewmen 144 kilometers off the coast of Quepos, Puntarenas province, in Costa Rica’s central Pacific.

After inspecting the boat authorities found a stash of cocaine weighing 1,151 kilos, said the Ministry of Public Security.

Those arrested in the incident are four Costa Rican fishermen between the ages of 30 and 40, residents of the province of Puntarenas and identified with the surnames Herrera, Buzano, Sánchez and Arias. The boat had a Costa Rican license plate and was named “Panameña II.”

Authorities will investigate the case to determine the origin and destination of the drug, as well as the possibility of more people being involved.

Those arrested may face prison terms of up to 20 years for the crime of drug trafficking.