A man was charged after US authorities spotted him with a gun in a North Carolina airport parking lot as President Barack Obama's plane was departing.
Joseph McVey, 23, was charged with going armed in terror of the public, a misdemeanour, said airport police Captain Kevan Smith.
Police saw McVey get out of a car about 2pm local time in the rental car return lot and he had a gun, Capt Smith said. He was taken into custody immediately and was being held at the county jail.
Security was heightened at the airport because President Barack Obama was leaving after vacationing in the state, headed to the memorial service for the 29 West Virginia coal miners killed in an explosion.
The suspect was nowhere near the president's plane, Air Force One, and was in a public area.
Mr Obama also visited 91-year-old evangelist Billy Graham's home after spending the weekend in Asheville.
McVey's car had strobe lights like a police car might, but the suspect is not in law enforcement, said Capt Smith.
The investigation into what McVey was doing with a gun and why his car was equipped with strobe lights is continuing, Capt Smith said. The Secret Service, the agency charged with protecting the President, had no comment on the arrest, deferring to airport police.
A jail officer did not have a hometown listed for McVey and said it didn't appear McVey had an attorney. His bond was set at 100,000 US dollars.
When McVey got out of the car, he was listening to a handheld scanner and radio that had a remote earpiece, Capt Smith said.
Police said he was monitoring local agencies and had formulas for rifle scopes on a note in his cup holder. Police did not immediately elaborate on what the formulas might mean.
McVey gave authorities an Ohio driver's licence, but a computer check failed to show the number was valid, police said.
When Officer Kaleb Rice asked him what he was doing, McVey told him he heard the president was in town and wanted to see him.
Mr Rice removed the firearm and took McVey into custody.
The investigation into what McVey was doing with a gun, with formulas for rifle scopes and why his car was equipped with police gear was continuing.