Authorities in Honduras say they are investigating the killing of Honduran Indian leader Bertha Caceres, who won the 2015 Goldman Environmental Prize for her role in fighting a dam project.

A member of her Indian council group says assailants broke into her home and shot Caceres to death early Thursday.

Tomas Membreno says at least two assailants participated in the killing in the town of La Esperanza.

Caceres was a mother of four and a Lenca Indian. She led opposition to a proposed dam on the Gualcarque river, considered sacred by the Lencas.

The project's backers have largely abandoned building plans.

Caceres had previously complained of receiving death threats from police, soldiers and local landowners because of her activism.