BANGKOK (AP) — Thai authorities are working to clean up an oil spill from a small tanker that sunk just southwest of Bangkok.

Arthit Boonyasophat, the provincial governor of Samut Sakhon, said Wednesday that the oil slick had reached a fishermen’s village and mangrove forest on the coast 40 kilometers (25 miles) southwest of Bangkok.

But he says workers have already scooped up 75 percent of the 1,500 liters (9 barrels) of oil and are working to finish the cleanup in the Gulf of Thailand.

Arthit says water seeped into the engine room of the medium-sized boat, causing it to capsize Monday.

Authorities were also trying to salvage the sunken boat. It sank about 4 kilometers (2.5 miles) from the coast.