Ten people were killed and 19 injured when a Greek fighter plane crashed during NATO training in Spain, the defence ministry said.
The F-16 crashed shortly after taking off at a training centre in Albacete, 260km southeast of Madrid.
Spanish Prime Minister Mariano Rajoy said that eight French nationals and two Greeks were killed in the incident.
The plane "was carrying out a (training) exercise when during take-off the plane lost power, crashing into the parking area for planes, crashing into various planes that were parked there," the defence ministry said in a statement.
"There are also quite a lot of people injured - 10 French people, 11 Italians," Rajoy said in an interview with Telecinco TV.
The ministry gave no further details about the cause of the crash.
Defence Minister Pedro Morenes was due to travel to the scene.
Two pilots on board were among the dead, according to Spanish media reports.
Other pilots and mechanics were underneath the plane in the parking area in French Mirage and Italian Alpha Jet planes, said the defence ministry.
"I am deeply saddened," NATO Secretary General Jens Stoltenberg said in a statement.
"This is a tragedy which affects the whole NATO family. I express my heartfelt condolences to the loved ones and the nations of those who lost their lives, and I wish a speedy recovery to the injured."
Five of the injured were taken to a specialist burns unit at La Paz Hospital in Madrid, while the others were treated at a hospital in Albacete.