There are confirmed cases of bird flu in dairy cattle in eight US states, according to the US Department of Agriculture
Thames Valley Police confirmed that there were no survivor in the crash of the aircraft with two people onboard each on Friday, BBC reported.
A spokesperson for the nearby Wycombe Air Park said both aircraft had come from there, the Guardian newspaper said.
Police did not give details of the victims and added it was 'too early' to determine the cause of the crash.
Andy Parry, a teacher in Aylesbury, told the BBC he was with students at the Waddesdon Manor near the site at the time of the crash.
He said they heard a 'massive bang' and saw debris in the sky.