Yemeni police have opened fire on Shiite protesters marching toward the prime minister's office in the capital, Sanaa, killing at least two people.

The shooting erupted during a rally on Tuesday by supporters of Shiite Hawthi rebels who have been fighting against Sunni tribesmen in the country's north.

As the demonstrators marched up to the government headquarters, the police first fired tear gas to try and disperse the crowds, then started shooting.

Medical officials said two people died. Witnesses at the scene said at least three were wounded by gunshots while several were injured in a stampede that erupted after the shooting, as the protesters tried to get away from the scene.

The officials and witnesses spoke on condition of anonymity as they were not authorized to talk to media.