A group of indigenous protesters in Peru’s remote Amazon (NASDAQ:AMZN) region attacked two oil tankers with gasoline bombs apparently because they are angry about changes by the government to social oil funds, the operator of the vessels said on Wednesday.

A dozen crew members from both tankers, one of which contained 40,000 barrels of crude, were also kidnapped by the assailants, according to a statement from Canada-based PetroTal.

PetroTal accused protesters affiliated with indigenous association Aidecobap of blocking an Amazon tributary preventing the passage of the two oil tankers, one of which was empty, while attacking them from canoes with gasoline bombs.

Aidecobap representatives were not immediately available for comment.

The attack occurred on Tuesday by an Amazon tributary in the Loreto region in northwest Peru, PetroTal said, with the oil originating from the country’s most productive field.

The two vessels, one operating under a Brazilian flag, were traveling along the Amazon to Brazil from PetroTal’s field in sparsely-populated Loreto, according to the company.

Carlos Maldonado, PetroTal’s social management manager, told local television that the protesters who boarded the tanker loaded with oil forced it to a town known as 7 de Julio, where it is currently being held.

Peru, which pumps about 43,000 barrels of crude daily, is one of Latin America’s smaller oil producers.

PetroTal has experienced past attacks from indigenous groups, many of which demand more benefits from oil exploitation and complain about oil spills contaminating the area.

The company said it gives 2.5% of profits from its local production to nearby communities.