A ramshackle church school collapsed in a shanty town on the outskirts of Haiti's capital on Friday, burying dozens in rubble and killing at least 75, many of them children.

The three-story La Promesse school caved in while class was in session, and some of the walls and debris crushed neighboring residences in the Nerettes community near Port-au-Prince, injuring still more, civil protection service official Nadia Blachard told Haitian radio.

Claire Lydie Parent mayor of Petionville, said the death toll now stood at 75 after rescue crews uncovered a classroom filled with students and a teacher.

Crowds of screaming and crying parents swarmed the ruins in the aftermath searching for their children. The work continued after nightfall with the help of UN peacekeepers, relatives and rescue services.

President Rene Preval said the poorly constructed building did not meet building standards, but the priority of authorities was to continue to hunt for those trapped under debris but still alive. He said buildings throughout Haiti were also at risk because of shoddy construction.

At the scene, crying and screaming parents searched desperately for their children while bodies of students lay crushed under blocks of concrete.

"It's like an earthquake," said Brazilian Major General Carlos dos Santos Cruz, the commander for UN troops in Haiti.

One boy was trapped by debris that pinned his legs. He begged the rescuers to "please cut my feet off," a firefighter said.

The roads around the school were so jammed with people looking for loved ones that some of the rescuers had to be brought in by helicopter.

"My son who is 15 years old, he's dead. He's my only son," sobbed 40-year-old Josiane Dandin. "I don't know what I'm going to do."

Another woman screamed for her missing 12-year-old daughter. "I don't know if she is dead or alive," she said.

More than 9,000 multinational troops and police make up a UN peacekeeping force sent to stabilize Haiti after its former president was driven out in a bloody rebellion in 2004.

The impoverished Caribbean nation lacks sophisticated rescue equipment. Haiti is also still struggling with the destruction wrought by four tropical storms and hurricanes that hit in quick succession this year, killing more than 800 people and destroying 60 percent of the crop harvest.

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