One person has been killed and several others injured in a clash between members of the Yaqui indigenous group divided over construction of a gas pipeline in northwest Mexico.

Sonora state public security chief Adolfo Garcia Morales said in a news conference late Friday that a protest began around 9 a.m. outside a school in Loma de Bacum. About 400 people between the two sides had gathered by noon.

Garcia says shots were fired and one man was killed. He says the conflict at the root of the clash is internal to the Yaquis.

State prosecutor Rodolfo Montes de Oca says the state is investigating the shooting, but the person who shot the gun remains unidentified.

Mario Luna, a spokesman for the Yaquis, said Saturday he was still gathering information.