A White House guard claims that an unknown individual jumped the fence into the White House grounds, according to White House correspondent to Reuters Jeff Mason.

The US Secret Service have corroborated the claim. An individual jumped the bike racks on the North Fence Line along Pennsylvania Avenue, according to a tweet. President Trump is believed to have been inside the Oval Office when the jump took place.

BREAKING: Secret Service moving all press inside the White House after security incident pic.twitter.com/LB0mucK9no — Trey Yingst (@TreyYingst) May 16, 2017

Fence-jumpers have proven themselves a persistent problem for the still-young Trump presidency. In March, 26-year-old Jonathan Tran jumped three fences and remained undetected on the White House grounds for 17 full minutes. Cans of mace were found on his person once he was apprehended.

Secret Service responding to an individual who jumped the bike rack along the North Fence Line of Penn Ave. Suspect in custody. — U.S. Secret Service (@SecretService) May 16, 2017

"Tran was able to scale that particular area of the fence without setting off alarms because they had been removed, leading to confusion among officers about his whereabouts and whether an intruder was inside the White House complex," insider sources told the Washington Examiner.

In April, the Secret Service enlarged the buffer zone between the public and the South White House fence to discourage jumpers.

According to USA Today, there have been roughly 100 attempts to unlawfully enter the White House grounds in the last three years, or a few a month. The vast majority of the jumpers have a history of mental or emotional illness.