MEXICO CITY (Reuters) - Gunmen killed eight fishermen in the popular Mexican surf resort of Puerto Escondido late on Monday, prosecutors said, in a rare shooting for a part of the country that has largely avoided serious gang violence.

The shark fishermen were in a house in the Pacific port when the gunmen entered and opened fire. Four were killed at the scene while the other four died soon after being taken to a local hospital, prosecutors from the southern state of Oaxaca said on Tuesday.

One of the main lines of investigation is whether the men also engaged in other activities at sea aside from fishing, the prosecutors said in a statement.

Monitored by federal police and the Mexican Navy, the coast of Oaxaca is a strategic point for traffickers moving drugs from Central and South America to the United States. Shark hunters fish offshore using vessels larger than ordinary fishing boats.

More than 120,000 people have been killed in Mexico in violence linked to drug gangs since the start of 2007.

Famous for the powerful waves that roll into the Zicatela beach, Puerto Escondido is a small resort frequented by visitors from the United States and Europe, particularly Italians.

(Reporting by Anahi Rama and Lizbeth Diaz; Writing by Alizeh Kohari; Editing by Dave Graham and Andrew Hay)