At least 25 people have been killed in an opposition protest in Madagascar.Opposition supporters had joined in a march through the capital Antananarivo to demonstrate in front of the presidential palace in support of sacked mayor Andry Rajoelina. Heavily armed troops opened fire on the protestors. The island has been rocked by violence since the end of January when anti-government riots broke out, led by Rajoelina. The 34-year-old ex-mayor, who was fired on Tuesday, has declared himself leader of a so-called transitional higher authority. He has successfully tapped into growing frustration in Madagascar against President Marc Ravalomanana, whom critics accuse of ruling like a dictator. Under Ravalomanana, Madagascar – the world’s fourth-largest island – has become a popular destination for tourists as well as foreign companies searching for minerals.