The troops waved pepper spray into the queue's front line.
Others standing atop a grubby white UN tank fired off steady rounds of rubber bullets to the air -- barely acknowledged by people shoving to get at precious food supplied by the US multi-faith Eagles Wings Foundation, which is providing disaster relief here.
The massive 7.0-magnitude earthquake on January 12 has left around a million people homeless, living in squalid tent camps in city parks, as hundreds of thousands of quake victims are being encouraged by the Haitian government to evacuate the destroyed capital.
When asked why there weren't greater numbers of UN troops to contain the hungry crowd, peacekeepers gestured that there weren't any more available to join them.
"Uno! Uno! Uno!" the Uruguayans -- part of the UN mission in Haiti (MINUSTAH) screamed in vain, holding up single fingers in a bid to form an orderly line.
The crowd instead moved as one, pushed strongly from behind, toward trucks laden with rice sacks emblazoned with the US flag and gallon jugs of vitamin-enriched soy oil.
A vomiting pregnant woman, still gesturing at her mouth to show hunger, was carried off by UN troops after collapsing out of the crush of bodies.
"In five minutes, we'll leave because they'll overrun us," a UN troop warned foreign press photographers.
When they did withdraw the crowd wildly swarmed to get at the 50 rice sacks left behind.
"It's all gone, they left nothing," wailed Geneve, an older Haitian woman clad in sweaty rags, when she finally reached the spot where trampled aid boxes laid empty.
She joined dozens of others to kneel on the trash-strewn street to pick up the last rice grains.
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