Seaplane with seven people on board plummets into the ocean near popular Australian tourist island

    Three people remain missing and four others have been injured after a seaplane crashed near a popular tourist spot.

    The aircraft plunged into the water near Thompson Bay on Rottnest Island, 19km off the coast of Perth, about 4pm on Tuesday.

    Emergency services including water police and two RAC Rescue helicopters were among dozens of first responders involved in the major search and rescue operation. 

    Of the four people rescued from the water, three were airlifted to hospital with serious injuries.

    Another three that were on board are unaccounted for.

    'Water Police and a number of civilian vessels provided immediate aid in an attempt to assist in the rescue,' WA Police Commissioner Col Blanch said.   

    'This is very much an unfolding situation and we are working to ascertain the details.' 

    The privately owned aircraft hit the water at Phillip Rock at the entrance of Thompson Bay. 

    The aircraft (pictured) plunged into the water near Thompson Bay on Rottnest Island, around 19km off the coast of Perth, about 4pm on Tuesday

    The aircraft (pictured) plunged into the water near Thompson Bay on Rottnest Island, around 19km off the coast of Perth, about 4pm on Tuesday

    Four people were rescued from the water with three airlifted to hospital (pictured)

    Four people were rescued from the water with three airlifted to hospital (pictured)

    Commissioner Blanch thanked witnesses, who assisted with the rescue effort. 

    'I do want to reassure the community that we have significant resources at [the] scene and we are doing everything that we can,' Commissioner Blanch said. 

    It's knot yet know why the plane crashed.  

    Shocked witnesses described the scenes as chaotic.

    'I saw two injured people. One guy was limping. He needed support to get off the boat. He would have been in his late 30s maybe,' Elisa Meazzi told Perth Now.

    'Then a woman in her 50s. Then one in her 20s.'

    Another witness heard the sounds of police and emergency service vehicles and saw water police surrounding the wreckage.

    'We didn't know what had happened because we were on the other side of the island, so we drove past and then we saw these helicopters and we thought there must have been a plane crash,' he said. 

    Others spotted the plane moving from side to side moments before the left wing hit the water, Nine News reports.  

    Four people including the three, who suffered serious injuries, were rescued from the water and have been airlifted to hospital following the light plane crash (pictured)

    Four people including the three, who suffered serious injuries, were rescued from the water and have been airlifted to hospital following the light plane crash (pictured)

    Phone from the scene showed the front half of the small seaplane submerged into the water. 

    Several parts of the plane were damaged, including the wings.

    The plane, which is a Cessna 208 Caravan 675, is operated by Swan River Seaplanes. 

    The aircraft is understood to have only arrived in Wester Australia on New Year's Day from Sydney.

    The plane can carry up to 14 passengers and the model was built and registered in 2016. 

    Some witnesses noticed the plane moving side to side before the left wing (pictured centre) hit the water

    Some witnesses noticed the plane moving side to side before the left wing (pictured centre) hit the water

    Swan River Seaplanes Director Kristy Bailey told the newspaper the company is working with authorities to ensure the safety of those on board the plane.  

    'Our priority is our pilot and passengers,' Ms Bailey said. 

    Rottnest Island, which is also known as Wadjemup, is a popular tourist spot which attracts thousands of visitors each year. 

    The island, which is also home to the world-famous marsupial quokkas, has a small airport and various companies offer flights to and from the mainland.