Doctors in Haiti battled on Monday in makeshift tents to save the lives of hundreds of injured people, including young children and the elderly, outside hospitals overwhelmed by a major earthquake that killed at least 1,419 people.
Authorities were racing to bring doctors to the worst-hit areas before a major storm arrived.
The 7.2 magnitude quake on Saturday destroyed thousands of homes and buildings. The Caribbean nation has yet to recover from another major earthquake 11 years ago and is reeling from the assassination of its president last month.
Dozens of churches, hotels, homes and schools were seriously damaged or ruined by the quake. Haitian authorities said on Monday afternoon that 1,419 fatalities had been confirmed with some 6,900 people injured and 37,312 houses destroyed.
In the south-western city of Jeremie, another badly hit area, doctors treated injured patients on stretchers underneath trees and on mattresses by the side of the road after healthcare centres ran out of space.
"We do have a serious issue," Jerry Chandler, the head of the Civil Protection Agency, told Reuters.
"There are very important facilities that are dysfunctional as we speak and those that are functional are receiving an overflow of patients."
The challenge facing Haiti has been exacerbated by the coronavirus pandemic, a severe economic downturn aggravated by fierce gang violence, and a political crisis that has engulfed the troubled nation after the assassination of the president, Jovenel Moise, on July 7.
Churches, hotels, hospitals and schools have been badly damaged or destroyed, while the walls of a prison were broken open by the violent tremors. At least 13,694 houses were destroyed, according to the Civil Protection Agency, suggesting the death toll could rise further.
In Les Cayes, a seaside town of about 90,000 people, rescuers in red hard hats and blue overalls pulled bodies from the tangled wreckage of one building, as a yellow mechanical excavator nearby helped to shift the rubble.
Haiti's Prime Minister Ariel Henry, who flew to visit Les Cayes, praised the dignity shown by people there even in the midst of their suffering.
"They are affected but resilient. They fight to survive," he said, and thanked international agencies and foreign governments for their support.
Nearby countries, including the Dominican Republic and Mexico, rushed to send food and medicine by air and across Haiti's land border. Colombia sent search and rescue personnel.
The US sent vital supplies and a 65-member urban search-and-rescue team with specialised equipment, said Samantha Power, the administrator of the US Agency for International Development.
The rescue and aid efforts will be complicated by Tropical Depression Grace, which is expected to lash Haiti with heavy rainfall on Monday. About 75 to 100 millimetres of rainfall is expected, which may trigger landslides and cause some rivers to flood, the Civil Protection Agency said.
At the Vatican, Pope Francis urged the international community to show support swiftly. "May solidarity from everyone lighten the consequences of the tragedy," he said at his Sunday blessing in St Peter's Square.
Haiti's government asked aid organisations not to set up makeshift camps and urged them to work through the planning ministry, an apparent attempt to avoid the mistakes made following the devastating 2010 earthquake that struck far closer to the sprawling capital, Port-au-Prince, and killed tens of thousands of people.
At Port-au-Prince airport, international aid workers, doctors and rescue workers boarded flights to Les Cayes. A US Coast Guard helicopter ferried the wounded.
The death toll is expected to rise as the telephone network has been down in more remote areas. In difficult-to-reach villages many houses were fragile and built on slopes vulnerable to landslides, said Alix Percinthe, from the ActionAid charity.
He said one local leader had informed him there were 47 deaths in his area not yet reported to regional authorities.
Footage of the aftermath of Saturday's quake, posted on social media, showed residents reaching into narrow openings in piles of fallen masonry to pull shocked and distraught people from the debris of walls and roofs that had crumbled around them.
Access to the worst-hit areas was complicated by a deterioration in law and order that has left key access roads in parts of Haiti in the hands of gangs. In a video posted on social media, one gang leader said the armed groups had declared a truce along the route to Les Cayes.
Mr Chandler said boats and helicopters were being used to bring in aid but the government was working to establish safe access by road. A first convoy of aid had made it through by land to the region of Les Cayes.
The United Nations called for a "humanitarian corridor" to be established so that aid can pass through gang-held territories.
Following Moise's assassination, which authorities have alleged was carried out by a group of largely Colombian mercenaries and Haitian accomplices, Mr Henry said officials would aim to hold elections for a new president as soon as possible.
However, reports this week suggested that the vote initially earmarked for next month would not take place until November. The chaos unleashed by Saturday's disaster is likely to make the task of holding prompt elections harder still.
Haiti has long been politically unstable and Haitians have also suffered from problems stemming from international aid efforts and peace-keeping deployments during the past decade.
A sexual misconduct scandal centring on Oxfam International blighted the record of charity workers in Haiti, while a cholera outbreak linked to UN peacekeepers led to thousands of deaths.