The two airmen killed when their Puma helicopter crashed in Yorkshire were both serving at RAF Benson, near Wallingford.

Flight Lieutenant David Sale, captain of the Puma, and Sergeant Phil Burfoot were killed when the helicopter crashed on Wednesday at about 8.20pm.

RAF Benson station commander Group Captain Paul Lyall, said: "Words cannot adequately express our grief at their loss. Our prayers and thoughts are with the families and loved ones at this time."

Flt Lt Sale had been with 33 Squadron since April 2006 and represented the airbase at both hockey and golf.

Grp Capt Lyall said: "He was a model officer and a professional pilot who could be relied on to do a job both effectively and in good humour. Dave was the life and soul of the party and will be sorely missed by everyone."

Welshman Sgt Burfoot - known as Taff - was a ground technician for Tornado fighter jets before joining 33 Squadron just three months ago.

Grp Capt Lyall said: "He was utterly dependable and highly professional, completing any task with a ready smile.

"He showed great potential in his fledgling career as a crewman and will be sorely missed by all his friends and colleagues."

Grp Capt Lyall said the cause of the accident remained unknown and a full investigation was in progress.

Nine passengers from 1 Brigade Infantry Training Battalion at Catterick were injured in the crash and taken to hospitals in the North East. Two of them were yesterday fighting for their lives.

The helicopter had 12 personnel on board, three RAF and nine Army.

It came down in a wooded area to the west of Catterick Garrison.

Air accident investigators were yesterday searching the wreckage for clues as to why it crashed.

A board of inquiry has been set up to find the cause of the accident.

Eyewitness Andrew Pavey said the helicopter came down like "a sack of potatoes".

He said: "We watched this helicopter quite rapidly go straight up into the air and it didn't sound right.

"It sounded like the engine was misfiring or something - it was making a hell of a racket."