Seven feared dead as US plane crashes in Pakistan
It appeared to be on a final approach to an airfield near Quetta when it crashed.
Pentagon officials said there is no evidence the plane has been brought down by hostile fire.
White House spokesman Mr Ari Fleischer said the aircraft, a KC-130 transport, went down in an airfield which has been used by coalition forces during the campaign in Afghanistan.
The Defence Department is investigating, he said.
President George W Bush is aware of the crash, he added.