The agency said in a statement that the person, who wasn't identified, was apprehended before reaching the fence on the north side of the White House along Pennsylvania Avenue.
President Donald Trump was in Florida at the time of both incidents.
It was a busy Saturday White House Secret Service officers.
The official could not say what the motive was or if the individual was intoxicated at the time of the incident.
A week ago, a man breached the White House grounds, claiming to be a friend of Trump, and was on the grounds for more than 15 minutes.
Two Secret Service agents tackled him to the ground and he was removed. Earlier in the day, a man was detained by the Secret Service after he jumped a bicycle rack in front of the White House.
In another related development, the Secret Service acknowledged on Friday that a laptop with sensitive information was stolen from its agent in NY.
"The Secret Service can not even keep one person off the grounds - what will they do if 40 terrorists charge the White House? In accordance with proper protocols, Secret Service personnel increased their posture of readiness", they added. The sources did not confirm that any device was found inside the vehicle.
In the letter, 'Tran mentioned Russian hackers and said he had information of relevance.
This is the third security incident at the White House in two weeks. He called the intruder a "troubled person".