Comoros security forces intensified their crackdown against anti-government rebels on the island of Anjouan on Thursday, with witnesses reporting heavy gunfire on the fourth day of clashes.Tensions in the Indian Ocean archipelago have flared in recent months as President Azali Assoumani's bids to extend term limits through planned constitutional changes that could see him rule for 11 more years.Assoumani won a referendum in July which allows him to push through reforms that include scrapping a rotation of the presidency between the country's three main islands after one term.Anjouan island, which had been due to take up the next presidency, is a stronghold of the opposition Juwa party that has accused Assoumani of becoming a dictator."We heard big explosions last night and also a lot of shooting this morning," French expatriate Anais Greusard told AFP."The difficulties seem to be concentrated in the centre" of Mutsamudu, the main city, she said, with some people fleeing their homes in the most dangerous streets.Mutsamudu's medina with its narrow, intersecting alleyways has become the epicentre of the fighting with security forces surrounding the rebel stronghold.Traffic outside the city centre was moving normally and the island's airport appeared to be open, witnesses said.Another resident living close to Mutsamudu said gunfire had continued into the early hours of Thursday in the most intense flare-up since the clashes began. 'We're without everything' Witnesses described water and power cuts in the medina and some surrounding areas, but traffic was circulating normally elsewhere in the city."We're without everything - but mostly water. The lack of water is unsustainable. It's been four days since we had water," a local woman living near the medina who had taken in family members from the volatile area told AFP.Residents had begun to stockpile bottled water and buckets with emergency supplies in response to the shortages, AFP saw.Interior Minister Mohamed Daoudou said on Wednesday that the situation was back to normal in Anjouan after three people were killed in the violence. Witnesses claimed that many more people had been injured in the clashes.He blamed "terrorists, as well as drug addicts and alcoholics" for the unrest.A Comoran opposition politician based in the neighbouring French-ruled island of Mayotte described the unrest on Anjouan as an uprising."The people are revolting... they won't stop shooting," said Ahmed Samir, a leader of the opposition Union for the Development of the Comoros (UPDC) party who added that the people wanted to oust Assoumani. Armed insurrection Samir claimed that around 40 armed men were leading the armed insurrection against government forces while witnesses described masked men with automatic weapons roaming the medina. A night-time curfew remained in place on the island.An AFP team in the normally bustling city of Mutsaumudu saw empty, dark streets and shuttered storefronts as residents opted to stay indoors.Assoumani, who came to power in a military coup and was elected in 2016, has indicated that he plans to stage polls next year which would allow him to reset his term limits and theoretically rule until 2029.The three Comoros islands - Anjouan, Grande Comore and Moheli - are located between Mozambique and Madagascar. They have endured years of grinding poverty and political turmoil, including a spate of coups, since independence from France in 1975.The fourth island, Mayotte, remains French territory.Two people from Anjouan arrived on a Mayotte beach with gunshot wounds in the early hours of Thursday, police said, though authorities could not confirm if they were injured in the ongoing fighting. Assoumani's government accuses the Juwa party of former Anjouan leader and island native Abdallah Sambi of being behind the unrest.The crisis was sparked on Monday when unidentified gangs erected barricades on the island which were then cleared by heavily-armed troops.The United Nations and African Union called for stalled talks between rival parties to resume.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.