In a scene of unspeakable horror, revelers on the perimeter of a crowded dance floor at a Jerusalem wedding watched Thursday night as the floor caved in, and hundreds of people instantly plunged three stories into a heap of concrete and steel.

The instant the floor collapsed was captured on videotape, which is being aired on Fox News Channel. 

At least 24 people have been killed, including a 3-year-old boy. More than 300 have been injured and countless others remain trapped in the rubble.

Four people — the building owner, an engineer, a designer and a contractor — were arrested Friday, police said. Israel TV's Channel Two said an initial inquiry pointed to negligence and an attempted cover-up.

Brick by brick, rescue workers are digging for survivors of the wedding of Assi and Keren Sror.

The couple had just become husband and wife and their 600 guests were dancing when the floor of the wedding hall caved in. Officials called it the worst accident of its kind in Israel's history.

The newlyweds, their families and friends fell into the abyss and plunged down three stories, as ceiling after ceiling buckled and crashed to the ground.

Screaming guests on the edges of the dance floor peered down into the crater in disbelief. The videotape shows one man scooping up a little girl in the mayhem. An elderly man walks right up to the large hole, and is escorted away by a woman.

The footage shows a man dancing with a baby wearing a white frilly dress. Later photos showed the baby, her face scratched, alive in the arms of a woman

"We were on people -- those poor people," said Tamar Revivo, 26, from her hospital bed Friday, where she was being treated for a fractured right ankle. "I'd see a hand. I'd see a person. They tried to get me out and I had to walk on them."

Sara Pinhas, a relative of the groom, said dancers had just lifted the father of the bride on a chair, a traditional part of the Jewish wedding celebration, when suddenly he fell, "and then we felt the whole building collapse, everything fell down."

"We managed to climb down the side of the building," she said.

By Friday evening, at least 24 bodies had been pulled from the pile of rubble, concrete slabs and twisted metal, said Yehuda Meshi Zahav, head of a group that collects remains after terrorist attacks. He said five bodies were found sitting around a table. A couple died hugging each other.

Several people were missing, and the death toll was expected to rise.

Maj. Gen. Gabi Ofir, in charge of the rescue operation, said 309 people were taken to hospitals with injuries. Hospital doctors said many children were among them, including a 3-month-old baby.

About 600 people were invited to the wedding, and another 50 to 55 people were working at the party, Ofir said.

The newlyweds were among the injured. Assi Sror was treated for minor injuries and released. But Keren Sror, carried out on a stretcher in her fluffy white dress, suffered hip and chest injuries and might need surgery, doctors said.

Jerusalem police ruled out the possibility of a terror attack, saying the building collapsed because of structural failure. According to first reports, the building appeared not to be up to construction codes. Several supporting columns in the halls had also been removed to enlarge the reception area, and the floor tiles had recently been replaced, the reports said.

It was the deadliest building collapse in Israel's history.

Prime Minister Ariel Sharon, visiting the scene Friday, said he would convene a Cabinet meeting Tuesday to consider the possibility of launching an official commission of inquiry.

"This was a shocking incident, one of the most difficult that occurred in Israel," Sharon said. "I would define this as a national disaster."

The Palestinian Authority sent its condolences to the Israeli government and offered to help with the rescue work. The gesture came at a time of bitter conflict between the two sides, after eight months of fighting that has killed hundreds, mostly on the Palestinian side.

At the scene of the wedding disaster, rescue workers aided by German shepherds searched for survivors and removed bodies from the rubble, carrying them on stretchers covered with blankets. Ofir said four people were rescued after several hours, and rescue efforts would continue for several days.

"We expect there are people alive under the rubble," Ofir said Friday.

The special Israeli army rescue unit that has been sent abroad in the past to dig out earthquake victims in India and Turkey was working at the scene.

Soldiers in yellow helmets used bulldozers, cranes and a conveyer belt to pull out the larger pieces of rubble and metal shards from the cavernous hole, but the mounds of debris were so unstable they tumbled at the touch of heavy machinery.

"I've been here since midnight, and all I've been doing is carrying out bodies," said rescue worker Yaakov Cohen.

The wedding was taking place on the top floor of the building, and the two floors below were not being used. The bottom floor was a parking garage.

Public Security Minister Uzi Landau said a committee of experts would be formed to investigate the cause. Taysir Ahmed el-Hadj told Israel television that he had done renovation work on the third floor, changing floor tiles. It was not clear if the renovations contributed to the collapse.

Jerusalem mayor Ehud Olmert said the building was constructed in 1986. He said his preliminary examination of the building file disclosed findings "that trouble me very much." He did not give details but suggested a criminal investigation may be required.

Police were questioning the owner of the hall, the engineer who designed it and others connected with the structure, Israel radio reported.

Engineer Shaul Nevo, a reserve army major taking part in the rescue, said the type of construction was to blame. He said several other buildings similarly built, with thin concrete layers, have collapsed in the past.

Ofir said it was the worst disaster involving a civilian building in Israel's history. On April 30, 1992, a mudslide collapsed the walls of a cafe in Jerusalem's Old City, killing 23 people and injuring 22.

--The Associated Press contributed to this report