Nov. 26 (UPI) -- A reported airspace violation that resulted in a lockdown of the White House on Tuesday turned out to be a false alarm, North American Aerospace Defense Command said.
Maj. Andrew Hennessy said NORAD identified an object flying near the White House that appeared to be an aircraft but that assessment was changed after a U.S. Coast Guard helicopter was sent to investigate.
"Upon further investigation, we found there was no aircraft," Hennessy said.
The U.S. Secret Service locked down the White House for about 30 minutes Tuesday after the suspected flying object violated the secure airspace surrounding the executive residence, officials said.
The agency said the lockdown was initiated when the object flew inside a prohibited perimeter around the White House. Authorities scrambled fighter aircraft and the U.S. Capitol was halted briefly as a result of the incursion.
The lockdown was lifted less than a half-hour later, the Secret Service said.
NORAD said the flying object was not deemed hostile.
"Senior interagency officials are monitoring the situation on a national event conference call," NORAD said during the lockdown. "Our jet fighters are on-site and responding."
Capitol police told CNN the flying object may have been a flock of birds based on how slowly it was moving and how it appeared on radar.
"How the flock of birds appears on a radar screen can be very similar to the radar 'look' of a small aircraft. This happens sometimes with older radar systems," retired Air Force Col. Cedric Leighton said.
Congress is in recess this week for the Thanksgiving holiday and most lawmakers were not on Capitol Hill Tuesday.
Airspace surrounding the White House has long been barred to commercial and private flights and is closely guarded by the Secret Service and U.S. Park Police.