NASHVILLE, Tenn. (WKRN) — The Federal Aviation Administration has classified the airspace around the site of Friday morning’s bombing in downtown Nashville as “National Defense Airspace,” saying “deadly force” could be used as a last resort against pilots appearing to pose a security threat.

An alert issued by the FAA warned pilots of the temporary flight restrictions for one nautical mile, which is approximately 1.15 miles, around the site of the explosion along Second Avenue North near Commerce Street.

Pilots not adhering to the restrictions “may be intercepted, detained and interviewed by law enforcement/security personnel,” according to the alert. It stated the FAA could impose civil penalties and suspension or revocation of airmen certificates, while the United States government could pursue criminal charges or “use deadly force” against the aircraft if it is determined that it “poses imminent security threat.”

The restrictions are effective Friday through 4:45 p.m. on Dec. 30.