A wooden boat packed with dozens of asylum seekers smashed apart on jagged rocks in heavy seas off an Australian island today, flinging screaming women and children into churning water and sending many to their deaths. 28 are believed to have died.

Christmas Island residents on cliffs above watched in horror as the boat broke apart with a crack, dumping passengers into huge waves that pounded them against the rocks.

"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.

Acting prime minister Wayne Swan said the vessel was a people smuggler's boat, but it was not clear how many people were on board or where they were from. "A number of people have been rescued but sadly, some bodies have been retrieved," Mr Swan said.

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 centre there.

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. The boat was about 20ft to 30ft long, with a cabin covered by a sheet of fabric or plastic.

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

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

He called the police and soon there were dozens of locals standing on the cliffs, wondering how they could help despite the storm and crashing waves.

He said the boat, carrying about 50 people, was tossed about 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," Mr Prince said.

"It was just horrible. People getting crushed. Bodies, dead children, the whole thing was pretty awful."

Mr Prince, who owns a dive shop, and other neighbours began hurling lifejackets into the water, 50 or 60 of them. 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, and needed stitches later, 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," Mr Foster said. "It was a pretty horrible situation."

Mr Foster, an electrician, saw around 50 people struggling against the 10ft 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.

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.