The RAF helicopter which crashed last night in North Yorkshire killing two people was based at RAF Benson near Wallingford, it emerged today.

The aircraft involved in the crash was a Puma helicopter from 33 Squadron, RAF Benson, according to the Ministry of Defence.

Twelve personnel were on board, three from the RAF and nine from the Army.

The helicopter came down in a wooded area to the west of Catterick Garrison at 9pm.

Air accident investigators were today searching the wreckage for clues as to why it crashed, and a board of inquiry has been set up to find the cause of the accident.

Two people were confirmed dead at the scene while the 10 injured were taken to surrounding hospitals in Darlington, Northallerton, Middlesbrough and Newcastle.

A spokesman for the Ministry of Defence said: "No further details about the personnel involved will be given until all families have been informed.

"The cause of the accident is still unknown and a full investigation is now in progress. "Our sympathies are with the families and loved ones of those involved."

RAF spokesman Michael Mulford added: "They (air investigators) will go through every possible detail, everything to do with the maintenance of the aircraft, everything to do with the crew hours and flying hours, weather conditions, mechanics and electrics - everything you can think of that might contribute to an accident."

North Yorkshire Police secured the scene, and the rescue operation involved aircraft from RAF Leconfield and RAF Boulmer, as well as a mountain rescue team from RAF Leeming.

Eyewitness Andrew Pavey told the BBC: "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."

The crash took place near Hudswell Grange, on the western edge of Catterick Garrison, but not within its grounds.

Concerned families of military personnel should contact the Ministry of Defence major incident number on 0845 7800 900.