Haiti’s capital has been racked by a week of heavy fighting between gangs, with the global medical charity Médecins Sans Frontières (MSF) warning that thousands of people were trapped without food or water in one district of Port-au-Prince’s notorious Cité Soleil slum. “We are calling on all belligerents to allow aid to enter Brooklyn and to spare civilians,” said Mumuza Muhindo, the MSF’s head of mission in Haiti, in a statement referring to the contested area within the sprawling Cité Soleil. About 20,000 people have fled their homes since May because of gang warfare, according to the UN. On Monday the interim mayor of Cité Soleil said more than 50 people had been killed last weekend and more than 100 wounded. Haiti has been mired in months of increasingly violent social unrest over fuel shortages. “Along the only road into Brooklyn, we have encountered corpses that are decomposing or being burned,” Muhindo said. “They could be people killed during the clashes or people trying to leave who were shot. “It is a real battlefield,” he said. “It is not possible to estimate how many people have been killed.” MSF reported that on 10 July it was able to evacuate 12 patients from a clinic in the besieged neighbourhood, including people with gunshot wounds, pregnant women and a child with an urgent health condition. On the streets, there are scenes akin to a war zone, as rival militias – some tacitly supported by the government and security forces – jostle for territory. “It’s getting worse day by day … There are firefights, bullet holes everywhere, and dead bodies,” said one of the slum’s residents. “If someone tries to leave, they can be beaten or killed, so people can’t go to the market. “Since my childhood, I’ve lived in Cité Soleil, but it’s never been so violent,” said the resident, who asked not to be named for fear of reprisals. “We have no police, no ambulances. We are completely on our own.” Witnesses told the Guardian there were burning tyres and gun battles in different areas of the city, and analysts say that without petrol available at pumps, the crisis will only worsen. Petrol stations across the country have been closed, and one major port terminal has had to shut down as a result of the violence. Many Haitians rely on petrol to fuel the generators that power their homes and businesses because of the lack of electrical infrastructure. “There are barricades downtown and midtown, and the gangs have been fighting heavily since [last] Friday in Cité Soleil,” said Louis-Henri Mars, founder of Lakou Lapè, a local peace-building organisation. “Some of the population moved out of Cité Soleil two nights ago.” The violence is the latest in a litany of woes facing the Caribbean country. Last Thursday, Haiti commemorated the first anniversary of the assassination of its president, Jovenel Moïse. In August, the country was struck by a 7.2-magnitude earthquake, which killed more than 2,200 people and destroyed or damaged 135,000 buildings across the country’s rural south. Since then, gang violence and kidnappings have plagued the capital, alongside fuel shortages. Despite such endemic problems, some observers see a path to reducing violence. Judes Jonathas, a programme manager in Haiti with the US-based aid charity Mercy Corps, said: “Let’s start by giving young people other alternatives, creating decent opportunities for them to earn a living; but this must be done with other long-term measures to straighten out the entire security and judicial system of the country, as well as work on an education of peaceful management of conflicts within the various actors of the country.”