Followers of the Shiite Houthi movement flee from tear gas used by the riot police to disperse them, in Sanaa
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Yemen: 'Four dead' as police fire on Houthi protesters

Escalating tensions between Yemen's government and the armed Shia Houthi movement are threatening to plunge one of the poorest countries in the Middle East into a wide-scale armed conflict.

On Tuesday, police shot at anti-government Shia protesters in the capital, Sanaa, killing at least four people, witnesses say.

Three years after a popular uprising toppled the 33-year rule of Ali Abdullah Saleh, Yemen's transition to democracy is facing one of its toughest challenges.

Mai Noman reports from Sanaa.