Perth's Australia Day celebrations have been marred after two people were killed when a stunt plane crashed on the Swan River in front of thousands of people waiting for the city's annual fireworks display.
The seaplane stalled and nose-dived into the water about 5pm, breaking up on impact, as revellers looked on in horror.
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Plane crash tragedy
Perth is coming to terms with the tragedy on the Swan that killed two people and forced the cancellation of Skyworks. Vision: Nine News Perth
Boats rushed to the fixed wing craft in a desperate effort to rescue survivors but police confirmed soon after that both the pilot and sole passenger were dead.
The City of Perth announced the cancellation of the foreshore fireworks, scheduled to begin at 8pm, a short time later out of respect for those killed and to "conserve the integrity of the crash site".
![Safety authorites will inspect the plane on Friday, which is still in the Swan River.](/web/20170128192329im_/http://www.watoday.com.au/content/dam/images/g/t/z/k/t/m/image.related.articleLeadwide.620x349.gtznsi.png/1485552270547.jpg)
WA Police acting commissioner Stephen Brown said it was very fortunate the plane didn't crash into the crowd or other boats on the water nearby.
"For reasons yet unknown, it's entered the waterway, thankfully without injuring anyone else on the ground or any other people who are here at the event," he said.
More than 300,000 people were expected to attend the popular Perth Skyworks show but large crowds already gathered had been urged to head home after the cancellation was announced, with extra public transport services organised to assist.
Authorities were unsure if the plane was performing as part of the planned City of Perth festivities.
![Earlier, people had flocked to the Perth foreshore to celebrate.](/web/20170128192329im_/http://www.watoday.com.au/content/dam/images/g/t/z/h/h/k/image.related.articleLeadwide.620x349.gtznsi.png/1485480927551.jpg)
Wanneroo hosts Australia's biggest citizenship ceremony
Earlier in the day, the nation's biggest citizenship ceremony took place in fast-growing Wanneroo in the city's north, where 800 residents from 49 countries became new Australians.
Debate over whether to change the date of Australia Day meanwhile reached fever pitch in WA, with the City of Fremantle firmly in the crosshairs of some for its bid to move celebrations to January 28.
Others, however, have praised it for trying to get people to think about celebrating nationhood in a more inclusive way.
As they did around the country, "Invasion Day" protesters against marking the First Fleet's January 26 arrival at Botany Bay gathered in Perth's Supreme Court Gardens.
"Today, all around Australia my people are marching," 77-year-old Aboriginal elder Uncle Ben said at the peaceful event.
"We don't want the 26th. That's the day the colonisers arrived here."
After lashing Fremantle council, Premier Colin Barnett said it was time to move on.
"Aboriginal people are now recognised on Australia Day at events throughout our country," he said.
"It means different things to different people but it is our national day and I think we would be foolish as a country to change it."
AAP