An Air National Guard F-16 Fighting Falcon jet crashed in southeastern Arizona on Tuesday, Arizona Air National Guard officials said.

Rescue efforts were underway after the fighter jet crashed at about 3 p.m. mountain time (5 p.m. EDT) some 20 miles northwest of the city of Safford, the Air National Guard said in a statement.

Graham County Sheriff P.J. Allred said he did not know the identity of the pilot, nor where the man was from.

The crash occurred during training exercises out of Tucson International Airport, the Guard said.

An interim safety board has been assembled by the U.S. Air Force to investigate the incident.

The crash was the second involving an F-16 Fighting Falcon flying from the 162nd Wing at Tucson International Airport, and the third F-16 crash in Arizona, since mid-2015.

The 162nd Wing is the Air Guard’s biggest F-16 training operation and conducts training missions across military ranges in Southern and Central Arizona.