The White House and the U.S. Capitol were put on temporary lockdown following an airspace violation in Washington D.C., according to law enforcement sources.

The lockdown began shortly before 8:30 a.m. and was lifted at about 9:12 a.m., according to the Capitol Police.

The Secret Service said in a statement that the brief lockdown was due to a "potential violation of the restricted airspace in the National Capital Region."

The North American Aerospace Defense Command initially said the aircraft "is not considered hostile at this time," but later clarified, "upon further investigation, we found there was no aircraft"

A spokesperson for NORAD said in a statement later Tuesday that the object could have been "a flock of birds or a weather balloon."

The event was "resolved without incident," the spokesperson said.

The North Lawn of the White House was temporarily cleared earlier Tuesday as the incident was investigated.