Doctores and search dogs, troops and rescue teams flew to devastated Haiti, a land of dazed, dead and dying people, finding bottlenecks everywhere, beginning at a main airport short on jet fuel and ramp space and without a control tower.
The international Red Cross estimated 45,000 to 50,000 people were killed in Tuesday's cataclysmic earthquake, based on information from the Haitian Red Cross and government officials.
Meanwhile, there is little sign of humanitarian supplies beyond the Port-au-Prince airport, and correspondents say there is increasing anger among survivors.
Many survivors were reported to be have spent a third night without shelter in the ruined capital.
Hard-pressed recovery teams resorted to using bulldozers to transport loads of dead.
Worries mounted, meanwhile, about food and water for the survivors.
“People have been almost fighting for water,” aid worker Fevil Dubien said as he distributed water from a truck in a northern Port-au-Prince neighbourhood.
A handful of rescue teams were able to get down to work, scouring the rubble for survivors.
In one “small miracle”, searchers pulled a security guard alive from beneath the collapsed concrete floors of the UN peacekeeping headquarters, where many others were entombed.
But the silence of the dead otherwise was overwhelming in a city where uncounted bodies littered the streets in the 80-degree heat, and dust-caked arms and legs reached, frozen and lifeless, from the ruins.
Outside the General Hospital mortuary, hundreds of collected corpses blanketed the parking lot, as the grief-stricken searched among them for loved ones.
Brazilian UN peacekeepers, key to city security, were trying to organise mass burials.
Patience was wearing thin among the poorest who were waiting for aid, said David Wimhurst, spokesman for the UN peacekeeping mission.
“They want us to provide them with help, which is, of course, what we want to do,” he said.
“But they see UN vehicles patrolling the streets to maintain calm, and not delivering aid, and “they're slowly getting more angry and impatient.”
In Washington, President Barack Obama announced “one of the largest relief efforts in our recent history,” starting with $100m in aid.
From Europe, Asia and the Americas, other governments, the UN and private aid groups were sending planeloads of high-energy biscuits and other food, tons of water, tents, blankets, water-purification gear, heavy equipment for removing debris, helicopters and other transport, and teams of hundreds of search-and-rescue, medical and other specialists.
But two days after much of this ramshackle city was shattered, the global helping hand was slowed by the poor roads, airport and seaport of a wretchedly poor nation.