(CNN) A Spanish fighter jet accidentally fired an air-to-air missile while flying over Estonia during an air-policing mission, a NATO official told CNN.

"The flight path, location and status of the missile are currently under investigation," the official said of Tuesday's incident. "(The) missile has built-in self-destruction mode, but it is not ruled out that it has landed."

The Estonian air force has launched a search operation to find the AMRAAM-type missile, which is thought to have possibly landed "40 kilometers north of Tartu."

Estonian Prime Minister Jüri Ratas on Facebook called the incident "extremely regrettable" while also calling the NATO air policing mission over the Baltic country "a very important and necessary part" of Estonia's national security.

The missile was fired from a Spanish Eurofighter Typhoon 2000.