All four people, including two children, onboard a light plane were killed on Sunday after the aircraft crashed into waters off Australia’s Queensland state, police said.

       The four-seater aircraft took off from Redcliffe airfield, north east of Brisbane for what was believed to be a “joy ride” but crashed at about 9am local time, said Queensland police inspector Craig White.

       It crashed off the end of the runway at Redcliffe, about 32km northeast of the main city of Brisbane.

       Officer White said the members of the 69-year-old pilot’s family were at the Redcliffe aerodrome at the time of the crash.

       “I understand it was a bit of a family day,” he told reporters on Sunday. “The family are deeply traumatised as you’d expect.”

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       Police are yet to confirm the identities of another man and the two other children, who Mr White said were "younger than teenagers", adding that they do not believe they were related to the pilot.

       Visuals showed the Rockwell International aircraft floating upside down in Moreton Bay after the crash.

       Officer White said the families got concerned when the plane did not return and they got the news through social media posts.

       “This is a tragic accident,” he said. “It’s the lead up to Christmas and this is the last thing that any family need to go through at this time of the year, at any time.”

       Australian Transportation Safety Board Commissioner Angus Mitchell said they are carrying out investigations to know the reason for the crash. A report into the likely cause of the crash would be completed in six to eight weeks.

       Queensland police commissioner Katarina Carroll said police and divers struggled as the plane was in a difficult position in the wetland. “The plane is in a very, very difficult situation, difficult position in the wetland area, and we have currently got police and divers travelling to that area, and that’s all I can say at this stage,” she said.