PORT-AU-PRINCE, Haiti – A week after Hurricane Matthew leveled swaths of western Haiti, the relief effort is finally gaining steam, with the flow of food and medicine increasing to cities that will serve as hubs for desperate outlying villages, aid workers and diplomats say.

The storm that struck on Oct. 3 killed hundreds of people and forced thousands from their homes, setting off the worst humanitarian crisis in this impoverished country since the devastating earthquake six years ago. Winds tore apart buildings and flooding has contaminated water supplies and helped spur a new outbreak of cholera along the coast, with at least 200 reported cases, according to the United Nations.

A man walks past the debris left by Hurricane Matthew in Haiti on Monday. Nearly a week after the storm hit, some communities have yet to receive any assistance. l

A woman walks as she sells bread near destroyed homes by Hurricane Matthew in Jeremie, Haiti on Monday, Oct. 10, 2016. Almost a week after Matthew's assault, power is still out, water and food are scarce, and officials say that young men in villages along the road between the hard-hit cities of Les Cayes and Jeremie are putting up blockades of rocks and broken branches to halt convoys of vehicles bringing relief supplies. (AP Photo/Dieu Nalio Chery)

“I’ve seen it from the air and it looks catastrophic,” U.S. Ambassador Peter Mulrean said in an interview on Tuesday. “I’ve seen it from the ground and it is heartbreaking.”

In some areas, residents have erected roadblocks with logs and brush to stop aid trucks and ransack supplies. Increasingly desperate survivors are pleading for food, water and shelter.

“There have been worrying instances of looting of international aid and assistance on their way to most affected communities,” said Ariane Quentier, spokeswoman for the U.N. Stabilization Mission in Haiti.

Haiti’s National Civil Protection office has increased the death toll nationwide from the hurricane to 473, but that seems likely to grow, and some estimates put it at over 1,000. Some 175,000 people are now living in shelters.

The World Health Organization announced Tuesday it was sending 1 million doses of cholera vaccine to Haiti. It said about one-quarter of the health-care facilities in southern Haiti had been destroyed or seriously damaged. Cholera can be deadly and is transmitted through contaminated water or food.

American officials say the priority for relief remains saving lives: providing food and clean drinking water, by truck, boat, or helicopter, to many communities that remain hard to reach.

A U.S. disaster response team of more than 50 people has bivouacked in the atrium of the U.S. Embassy here, while the American military is working out of the airport, with about 425 affiliated personnel

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