Police arrested the owner of a Haitian school that collapsed on top of students and teachers during school hours, killing at least 88 people and launching a frantic search for survivors amid tons of concrete rubble.

Fortin Augustin, the preacher who owns and built College La Promesse in suburban Port-au-Prince, was arrested late Saturday and charged with involuntary manslaughter, said police spokesman Garry Desrosier.

Augustin was being held at a police station in Haiti's capital as a U.S. rescue crew searched overnight for survivors of Friday's collapse of the three-story building, which normally holds 500 students and teachers.

In a rare moment of joy in a grim task, Haitian rescuers pulled four children alive Saturday from the rubble and cradled them in their arms as they ran toward ambulances, said U.N. police spokesman Andre Leclerc.

Leclerc said he did not know the extent of the injuries to the two girls, ages 3 and 5, and two boys, a 7-year-old and a teenager. But he added the 3-year-old had a cut on her head and seemed to be OK.

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"She was talking and drinking juice," Leclerc said.

Nadia Lochard, civil protection coordinator for the western region that includes Petionville, said the death toll rose to 84 on Saturday, with 150 others injured and many more still missing.

Later, U.S. rescuers using digital cameras on long poles to look under the rubble found six or seven bodies, but think that two of them were already included in Lochard's death toll, said Evan Lewis, a member of the team from Fairfax County, Virginia.

In the two days of rescues, parents clutched pictures of their children as they watched rescue workers sidestep human limbs sticking out from the rubble. Riot police chased away several Haitians who found their way past police barriers and tried to excavate the site themselves.

Roughly 500 students typically crowded into the hillside school, which had been holding a party the day of the collapse, exempting students from wearing uniforms and complicating efforts to identify their bodies, Lochard said.

Thousands of Haitians cheered and shouted directions as trucks carried oxygen and medical supplies down the mountain road Saturday. By nightfall, hundreds stood in the shadows across a ravine behind the collapsed school watching rescuers pick through the rubble amid floodlights.

Angelique Toussaint kept vigil on a rooftop overlooking the rubble Saturday and prayed that her 13-year-old granddaughter, Velouna, would be saved. Her three other grandchildren were found alive on Friday, and one granddaughter underwent an operation for a severely broken leg.

Dressed in her white church clothes, the 55-year-old Roman Catholic said she had attended a group prayer for missing children. Velouna's parents had gone home, exhausted from the oppressive heat and endless waiting as rescuers struggled to work around a hanging concrete slab that could not be safely removed.

"I think they're doing a good job. It's a little slow, but I'm relieved all these people are helping," Toussaint said.

Local authorities used their bare hands to pull bleeding students from the wreckage before heavy equipment and international teams arrived late Friday and Saturday to help, including some 38 search-and-rescue officials and four rescue dogs from Virginia. France also sent a team of 15 firefighters and doctors from the nearby island of Martinique.

"These guys are the real experts," said Alexandre Deprez, acting director for the U.S. Agency for International Development in Haiti, which flew in the U.S. rescuers. "We've done everything we've possibly can."

Neighbors told French rescuers they'd heard children's voices under the rubble on Friday night and tried to pass them some cookies. But at that moment, the teetering ruins shifted and crashed down, silencing their cries, said Daniel Vigee, head of the Martinique-based French rescue team.

And as they readied to work through the night on Saturday, U.S. rescuers only heard silence, said Capt. Michael Istvan, operations chief for the Fairfax County Urban Search and Rescue team.

President Rene Preval, who has visited the concrete school three times since its collapse, said poor construction and a lack of steel reinforcements were to blame and warned that structures throughout Haiti run a similar risk.

"It's not just schools, it's where people live, it's churches," Preval he told The Associated Press as crews picked through the wreckage.

Parents said they had toiled endlessly to afford the school's $1,500 tuition in hopes of empowering their children to someday escape poverty in the capital's hillside suburb.

Haiti, the poorest and most politically tumultuous country in the Western Hemisphere, has struggled this year to recover from riots over rising food prices and a string of hurricanes and tropical storms that killed nearly 800 people.