The White House was shut down for a brief period Monday after someone threw a container over the north fence on Pennsylvania Avenue, WTOP reported. A woman was detained and placed in handcuffs, the Associated Press added.

The object reportedly had pieces of paper inside. Firetrucks and a hazardous materials response unit responded to the scene, which is typical when any potentially dangerous object is tossed over the fence of the Executive Mansion.

President Barack Obama was at the White House when the lockdown occurred. He had just returned from making a Memorial Day speech at Arlington National Cemetery.

The Secret Service did not immediately respond for comment, but it’s far from the first time such a lockdown has occurred because of possible security threats on the White House’s perimeter in recent years.

Incidents have ranged from frightening to downright bizarre, as USA Today noted. Many recall the 2014 occurrence when a knife-wielding man jumped over the fence, ran across the lawn and made it inside the White House before agents grabbed him. On the strange side, a man wearing a Pikachu hat jumped over the fence and was then arrested on the North Lawn. Last Thanksgiving, a man was arrested after he scaled the fence, saying he had to deliver a message.

Just 10 days before Monday’s incident, an intruder was shot outside the White House gates, prompting a lockdown. Obama was golfing at Andrews Air Force Base in Camp Springs, Maryland, when it occurred.

What is being done about the porous perimeter? Sharper spikes were added to the fence last summer to discourage intruders, and the Secret Service didn’t stop there: It suggested a new design with "intrusion detection technology."

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