The bodies of four men killed in a crash between a helicopter and plane have been recovered from the site.
The aircrafts collided over Waddesdon Estate, near Aylesbury, Buckinghamshire, on Friday. One of the victims was Capt Mike Green.
Thames Valley Police said it would not confirm the other men’s identities but said one was a Vietnamese national.
Post-mortem examinations, due to begin later, are expected to last several days, a spokesman said.
He added the force was working with “military support” to remove the wreckage.
An investigation by the Air Accident Investigation Branch into the cause of the crash is ongoing.
Supt Rebecca Mears said: “Our thoughts remain with the families of the men who have tragically lost their lives.
“Specially-trained officers are continuing to offer their support to the families of the victims affected, three of whom we understand to be British nationals, one of whom is a Vietnamese national.
“Work will today focus on removing the aircraft from the scene.”
Capt Green was conducting a flight instructor course with a student when they both died, his employer Helicopter Services said on Facebook.
The firm said it was “devastated” by his death.
The helicopter and the Cessna plane both took off from Wycombe Air Park, also known as Booker Airfield, which offers flight training.
It is about 20 miles (30km) from the site of the crash.
Three of the victims’ families visited the site of the wreckage, which is scattered across a wooded area, on Saturday.