Costa Rican authorities declared an emergency after a ship carrying 180 tons of ammonium nitrate sunk off the country's Pacific coast.

The National Emergency Commission (CNE) urged people to avoid swimming at beaches and suspend fishing in the region off the port of Puntarenas, 90 kilometers (55 miles) west of the capital.

The CNE said the accident occurred on Saturday when the boat sank in heavy seas. Two crew members were rescued without incident, the CNE said.

Ammonium nitrate is often used in the manufacture of fertilizers and explosives, and can be dangerous to health in cases of direct contact with the chemical.