A wooden boat packed with dozens of asylum seekers smashed apart on jagged rocks in heavy seas off an Australian island on Wednesday, flinging screaming women and children into churning whitewater and sending many people to their deaths.

Christmas Island residents on a cliff above watched in horror as the boat broke apart with a crack, dumping passengers into monstrous waves that pounded them against the rocks. At least 30 people were injured.

"It was just horrible. People getting crushed. Bodies, dead children, the whole thing was pretty awful," island resident Simon Prince said.

Rescue efforts were under way and Australian government agencies released scant details on the incident.

It was not known how many people were aboard the boat, how many were rescued, or how many were dead or missing. Joeley Pettit-Scott, a spokeswoman for the Royal Flying Doctor Service, said she heard unconfirmed reports of 50 people dead, but did not know the source of that information.

"While many details about this tragedy are still unconfirmed, I understand there have been a large number of fatalities and numerous injuries to those aboard the vessel, including women and children," Western Australia state Premier Colin Barnett said in a statement.

The Royal Flying Doctor Service sent doctors to the island to treat the 30 injured victims, Pettit-Scott said. Three patients were critically injured, two men with head injuries and one woman with blunt abdominal trauma, she said.

Acting Prime Minister Wayne Swan said the vessel was a people smuggler's boat, but it was not clear where the passengers were from.

Christmas Island is a remote Australian territory closer to Indonesia than the Australian mainland and a frequent target of refugee hopefuls, who are housed in a detention center there. Australia is a prime destination for people from poor, often war-ravaged countries such as Afghanistan who want to start a new life.

Photos and videos taken by witnesses at the scene show the wooden boat crashing into the rocks and breaking apart. The images also show people floating in the water amid the wreckage. It is unclear if they are alive or dead. The boat was about 20 to 30 feet (6 to 9 meters) long, with a cabin covered by a sheet of fabric or plastic.

Prince, who lives next to the cliff where the boat crashed, told the AP he was woken early Wednesday by what he thought were cheers. He walked to the cliff and instead heard cries for help from a boat just offshore.

"The engine had failed," Prince said. "They were washing backward and forward very close to the cliffs here, which are jagged limestone cliffs, very nasty."

Prince called the police and soon there were dozens of locals standing on the cliff, wondering how they could help despite the storm and crashing waves. He said the boat, carrying about 50 people, tossed for an hour before it finally hit the rocks at the base of the cliff.

"When the boat hit the cliff there was a sickening crack. All the people on board rushed to the land side, which is the worst thing they could do, but I don't think anybody could swim. I think there were about two lifeboats on board this thing," Prince said.

Prince, who owns a dive shop, and other neighbors hurled about 50 or 60 lifejackets into the water. But many just floated away. Some would-be rescuers were injured on the rocks while trying to get the lifejackets to those in the water, he said.

Resident Michael Foster watched in horror as women and children screamed out for help in the churning seas below.

"They had lifejackets on them, but the water was just pushing them up ... and throwing them towards the rocks," Foster told the AP. "It was a pretty horrible situation."

Foster, an electrician, saw around 50 people struggling against the 10 foot (3 meter) waves when he first arrived at the cliff, but the currents soon began to sweep them away. He counted around 10 bodies that appeared to be dead. In the churning whitewater, it was impossible to tell whether they were women or men, he said.

The Australian Federal Police would say only that they had responded to a "maritime incident" involving a suspected illegal vessel on the island. The department declined to comment further.

"There is an ongoing situation which involves a rescue of people off Christmas Island. Our paramount priority is the safety of all involved," the Customs and Border Protection Service said in a statement. Officials with the agency declined to elaborate.

Prince said Navy and Customs vessels were on the other side of the island helping another boat of asylum seekers in calmer seas and took awhile to respond to the calls for help.

"Eventually the Navy did come around and start picking people out of the water but it was too late for some," Prince said.

Asylum seekers who illegally enter Australian waters by boat are sent to Christman Island's detention center, or detention centers on the Australian mainland while their refugee claims are reviewed.