The US Navy pilot whose bombs killed six people in a training accident in Kuwait received the go-ahead from a US forward air controller.
The officials said the controller, whose job is to direct a pilot to a ground target, gave the pilot the all clear as he approached.
However, seconds later, apparently realising a mistake had been made, the controller called out to abort the mission but it was too late.
It is not clear whether the controller was among those killed.
The US Army Central Command, which is responsible for American military operations in the Persian Gulf area, has appointed a three-star general to lead an investigation.
Rear Admiral Craig Quigley, the chief Pentagon spokesman, said he did not know in detail the sequence of events that led to the fatal accident on Monday evening at the Udairi training range in northern Kuwait.
PA