More than 10,000 people in Haiti have been internally displaced in the last week as armed gangs operating in and around the capital, Port-au-Prince, ramp up attacks on areas they do not yet control, according to U.N. migration agency estimates on Thursday.

The agency had said at the start of September that more than 700,000 people were internally displaced across the Caribbean nation, nearly double the figure six months earlier.

Gangs have in the last week been ramping up attacks on a number of towns outside the capital, where much of the city and its suburbs are under the control of various violent armed groups united under a common alliance known as Viv Ansanm.

The conflict is fueling famine-level hunger in parts of the population as gangs take over farmlands and block off transport routes, while people forced to flee their homes — often to host families or makeshift camps — can no longer depend on steady income to afford food.

While the United Nations authorized an international force to help Haiti's police take back control from the gangs, the mission has been poorly resourced and has produced scant results.

Haiti's leadership has requested the force be converted to a formal peacekeeping mission to shore up resources, an initiative that was blocked last month by China and Russia.

Gangs who previously targeted national police, civilian self-defense groups and state infrastructure also have begun targeting foreign vehicles.

The U.S. Embassy in Haiti told Reuters that on Monday two of its armored vehicles had been targeted by gang gunfire.

One was hit by multiple rounds, although no one was hurt or injured.

A U.N. helicopter with 18 people on board was also shot at and hit with multiple rounds on Thursday, although no one was injured, the Miami Herald reported. The U.N.'s Haiti office did not immediately respond to a request for more information.