Port-au-Prince, Haiti ? Doctors and search dogs, troops and rescue teams flew to this devastated land of dazed, dead and dying people Thursday, 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. 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 neighborhood.

From Virginia, from France, from China, 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 U.N. 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 morgue, hundreds of collected corpses blanketed the parking lot, as the grief-stricken searched among them for loved ones. Brazilian U.N. peacekeepers, key to city security, were trying to organize mass burials.

Patience already was wearing thin among the poorest who were waiting for aid, said David Wimhurst, spokesman for the U.N. peacekeeping mission.

“They want us to provide them with help, which is, of course, what we want to do,” he said. But they see U.N. vehicles patrolling the streets to maintain calm, and not delivering aid, and “they’re slowly getting more angry and impatient,” he said.